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Multiple mechanical factors have been implicated in the initiation of exercise-induced muscle injury. Although high absolute force levels are associated with greater injury, the importance of high force per active area independent of absolute force remains to be determined, especially in humans. Purpose: This study sought to examine the role of specific force in muscle injury when peak eccentric force and total eccentric force were matched between two exercise bouts. Methods: Ten subjects (six men, four women) performed 80 electrically stimulated (EMS) eccentric contractions of the right and left quadriceps femoris (QF) through a 90 degrees arc at [equivalent to] 45 degrees·s[-1]. Specific force was manipulated by applying 25-Hz EMS to one thigh and 100-Hz EMS to the contralateral thigh, whereas force production was matched by lowering the EMS amplitude during the 100-Hz bout. T2 magnetic resonance images of the QF were collected before and 3 d after the eccentric exercise bouts. Injury was assessed via changes in isometric force and ratings of soreness in the QF over the course of 28 d after exercise and by determining changes in T2 relaxation time and muscle volume 3 d after exercise. Results: The 100-Hz EMS induced a greater force loss (P < 0. 05), soreness (P < 0.05), change in muscle volume (P = 0.03), and volume of muscle demonstrating an increase in T2 (P = 0.005) compared with 25-Hz EMS. Conclusions: Our findings suggest that in humans, high specific force potentially plays an important role in the initiation of exercise-induced muscle injury. [ABSTRACT FROM AUTHOR]

Repeated bouts of eccentric exercise reduce the amount of exercise-induced muscle injury. Purpose: This study sought to evaluate the importance of neural adaptations by comparing the repeated bout effect on muscle injury caused by voluntary and electrically stimulated eccentric exercise. Methods: Sixteen subjects (nine men, seven women) were assigned into two groups; electrical stimulation (STIM) and voluntary (VOL). Each group performed 2 identical bouts of 80eccentric contractions of the quadriceps femoris (QF) through a 90 degrees arc at [equivalent to] 45 degrees·s[-1], separated by 7 wk. T2-weighted magnetic resonance images of the QF were obtained before and 3 d after each exercise bout. Injury was assessed by determining changes in T2 relaxation time and muscle volume 3 d after exercise, and changes in isometric force and ratings of soreness for 28 d after exercise. Results: The initial bout of exercise caused significant changes in T2 relaxation time, isometric force, and ratings of soreness in both STIM and VOL groups (P < 0.05). After the repeated bout, significantly smaller changes were noted in soreness ratings (P < 0.05), mean change in T2 (P<0.05), and percentage of the QF demonstrating an increase in T2 (P < 0.05) compared with the initial bout in both exercise groups. Conclusions: A repeated-bout effect was observed after electrically stimulated exercise, and the magnitude of the effect was similar to that observed with voluntary exercise. This suggests that the primary mechanism for the reduction in muscle injury after repeated exercise bouts is not related to changes in muscle recruitment and is potentially related to structural changes within the muscles. [ABSTRACT FROM AUTHOR]

Background: There is a high prevalance of hypertension in adults with with cerebral palsy (CP). However, less is known about blood pressure in children with CP., Objective: The aim was to determine if blood pressure is elevated in children with CP and whether it is related to adiposity and physical activity., Methods: Thirty children with spastic CP (5-11 y) and 30 age-, sex-, and race-matched typically developing control children were studied. Resting systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate were measured, and mean arterial pressure (MAP) was calculated. Visceral fat mass and total body fat mass index (FMI) were determined using dual-energy X-ray absorptiometry. Physical activity was assessed using accelerometer-based monitors., Results: Children with CP had higher DBP and heart rate than controls (p < 0.05). DBP percentile and MAP were also higher in children with CP when BMI was statistically controlled. Children with CP and elevated blood pressure or hypertension (n = 8) had 56% more visceral fat mass than children with CP and normal blood pressure (n = 22; p < 0.05). In the groups combined, blood pressure was directly related to visceral fat mass and FMI, and inversely related to physical activity (p < 0.05). However, in children with CP alone, only visceral fat mass was related to blood pressure (p < 0.05)., Conclusions: Children with CP have higher resting blood pressure than typically developing children. The higher blood pressure is related to higher visceral adiposity. Careful blood pressure screening should start during childhood in individuals with CP., Competing Interests: Declaration of competing interest The abstract of this manuscript was presented as a poster at the Southeast Regional Clinical and Translational Science Conference 2023. This study was supported by The Eunice Kennedy Shriver National Institute of Child Health and Human Development (grant number HD090126) and University of Georgia Athletic Association. All authors declare no conflict of interest., (Copyright © 2024. Published by Elsevier Inc.)

The near-infrared spectroscopy (NIRS) vascular occlusion test (VOT) assesses microvascular reperfusion. Two strategies have been used to quantify reperfusion following reactive hyperemia, but it is unclear whether both yield similar results when comparing biological sex. This study aimed to determine whether sex differences in NIRS-based microvascular reperfusion are similarly apparent using the 10-s reactive hyperemia slope of the tissue saturation index (StO 2 ) signal (slope 2) and the halftime to maximal reperfusion (T ½). Healthy, recreationally active males ( n = 31) and females ( n = 31) between 18 and 82 years took part in this study. A NIRS VOT was performed on the tibialis anterior muscle, and reperfusion was quantified using slope 2 (% s -1 ) and T ½ (s). Adipose tissue thickness (ATT) was higher in females ( P = 0.009), which was associated with a lower StO 2 ( P = 0.001) and oxygenated hemoglobin (O 2 Hb) ( P = 0.05) signal range. The StO 2 slope 2 was significantly steeper in males versus females ( P = 0.001) but not after correcting for ATT ( P = 0.295). There were no sex differences in StO 2 T ½ ( P = 0.067) or O 2 Hb T ½ ( P = 0.197). In a subset of males ( n = 26) and females ( n = 21) with similar ATT, there were no sex differences in StO 2 slope 2 ( P = 0.068), StO 2 T ½ ( P = 0.491), or O 2 Hb T ½ ( P = 0.899). An ATT-corrected StO 2 slope 2 or the T ½ approach is recommended for analysis of NIRS-based microvascular reperfusion when differences in ATT are present between sexes. NEW & NOTEWORTHY Sex differences in near-infrared spectroscopy (NIRS)-based microvascular reperfusion have been previously reported. We found that greater adipose tissue thickness in females reduces kinetic measures of NIRS-based microvascular reperfusion. Sex differences are eliminated when performing an adipose tissue thickness correction, when the NIRS signal range is accounted for, or when adipose tissue thickness is similar between sexes. This highlights the importance of considering factors that affect NIRS signals, such as adipose tissue thickness, when drawing comparisons between groups.

Purpose: This study measured the time course mVO2max following both maximal and submaximal exercise., Methods: Healthy male and female participants were tested (n = 12 maximal and n = 8 submaximal exercise). A NIRS device was placed on the left medial gastrocnemius. Participants performed either one minute of maximal, rapid (~2 Hz), or submaximal (~0.37 Hz) plantar flexion exercise on a custom pneumatic ergometer. mVO2max was measured before and immediately after exercise. mVO2max measurements consisted of four incomplete recovery curves of muscle metabolism taken after 30 seconds of electrical muscle stimulation except in the first post-exercise trial. The four recovery curves were collected 50-, 156-, 260-, and 366-seconds post-exercise, each producing a mVO2max rate constant., Results: After maximal exercise muscle acceleration decreased to 52 + 18% (p = 0.001) of pre-values. mVO2max was reduced from the pre-exercise mean at the first post-trial (2.16 + 0.44 min-1 to 1.21 + 0.52 min -1, p < 0.001). The fourth trial showed recovery from the first (2.2 + 0.46 min-1 vs 1.21 + 0.52 min-1, p < 0.001) and was not significantly different from pre-exercise values (2.2 + 0.46 min-1 vs 2.16 + 0.44 min-1, p = 0.41). No change in acceleration or mVO2max was seen after submaximal exercise (p > 0.05)., Conclusions: The 56.7% reduction in mVO2max supports the hypothesis that in young, healthy individuals a minute of maximal exercise transiently impairs mVO2max which then recovers within six minutes. The NIRS method shows promise in tracking time course changes in mVO2max and warrants further investigation of the transient effects of exercise on mVO2max., Competing Interests: Conflict of Interest and Funding Source: This study received partial support from the Michael E. Penland Family Undergraduate Research Award and CURO scholarship awards from the University of Georgia. K. K. McCully is president of InfraredRx, Inc., a NIRS-based, software analysis company., (Copyright © 2024 by the American College of Sports Medicine.)

Background: The Multiple Sclerosis Walking Scale-12 (MSWS-12) has typically been delivered through paper-and-pencil or computer-based administration., Purpose: This study examined the validity of inferences from scores derived via a telephone administration of the MSWS-12 applied as part of screening of participants with walking dysfunction into a clinical trial of exercise training in MS., Method: The MSWS-12 was administered on two occasions separated by approximately 2 weeks through the telephone and then in-person (i.e., computer-based administration). Participants further completed the Patient Determined Disease Steps (PDDS) scale, timed 25-foot walk (T25FW), six-minute walk (6MW), Modified Fatigue Impact Scale (MFIS), and Multiple Sclerosis Impact Scale-29 (MSIS-29), and underwent a neurological exam for generating an expanded disability status scale (EDSS) score. The primary set of data (Full Sample) for analyses included all persons who passed the telephone screening for inclusion with MSWS-12 scores between 25 and 75 (N = 374). The secondary set of data (Truncated Sample) included only persons with MSWS-12 scores between 25 and 75 for both the telephone and computer administrations of the MSWS-12 (N = 248)., Results: The results in the Full Sample indicated a difference in overall and item levels scores between the telephone and computer data collections, and the computer version had higher internal consistency and stronger unidimensionality. Nevertheless, MSWS-12 scores from both modes of administration had comparable correlations with the T25FW, 6MW, EDSS, PDDS, MFIS, and MSIS-29, but the correlation between the two MSWS-12 administrations did not approach unity. There was a systematic difference in scores between telephone and computer administrations across levels of walking dysfunction based on a Bland-Altman plot, and the difference was predicted by MFIS physical, 6MW, and EDSS scores. The comparison of results between the Full and Truncated Samples suggested that the primary analysis might have been influenced by the larger range of scores on the computer than telephone administrations of the MSWS-12., Conclusion: The telephone administration of the MSWS-12 provides an efficient and cost-effective measure of walking dysfunction in persons with MS., Competing Interests: Declaration of competing interest The authors report no conflicts of interest in the publication of this paper., (Copyright © 2024. Published by Elsevier B.V.)

Background: Phosphocreatine dynamics provide the gold standard evaluation of in-vivo mitochondrial function and is tightly coupled with oxygen availability. Low mitochondrial oxidative capacity has been associated with health issues and low exercise performance., Methods: To evaluate the relationship between near-infrared spectroscopy-based muscle oxygen dynamics and magnetic resonance spectroscopy-based energy-rich phosphates, a systematic review of the literature related to muscle oxygen dynamics and energy-rich phosphates was conducted. PRISMA guidelines were followed to perform a comprehensive and systematic search of four databases on 02-11-2021 (PubMed, MEDLINE, Scopus and Web of Science). Beforehand pre-registration with the Open Science Framework was performed. Studies had to include healthy humans aged 18-55, measures related to NIRS-based muscle oxygen measures in combination with energy-rich phosphates. Exclusion criteria were clinical populations, laboratory animals, acutely injured subjects, data that only assessed oxygen dynamics or energy-rich phosphates, or grey literature. The Effective Public Health Practice Project Quality Assessment Tool was used to assess methodological quality, and data extraction was presented in a table., Results: Out of 1483 records, 28 were eligible. All included studies were rated moderate. The studies suggest muscle oxygen dynamics could indicate energy-rich phosphates under appropriate protocol settings., Conclusion: Arterial occlusion and exercise intensity might be important factors to control if NIRS application should be used to examine energetics. However, more research needs to be conducted without arterial occlusion and with high-intensity exercises to support the applicability of NIRS and provide an agreement level in the concurrent course of muscle oxygen kinetics and muscle energetics., Trial Registration: https://osf.io/py32n/ ., Key Points: 1. NIRS derived measures of muscle oxygenation agree with gold-standard measures of high energy phosphates when assessed in an appropriate protocol setting. 2. At rest when applying the AO protocol, in the absence of muscle activity, an initial disjunction between the NIRS signal and high energy phosphates can been seen, suggesting a cascading relationship. 3. During exercise and recovery a disruption of oxygen delivery is required to provide the appropriate setting for evaluation through either an AO protocol or high intensity contractions., (© 2024. The Author(s).)

Background: Near-infrared spectroscopy (NIRS) is a non-invasive tool used to measure blood flow in peripheral tissues. More information on inter-rater agreement and test-retest reliability of NIRS-based reperfusion assessments is needed., Purpose: To assess inter-rater agreement for NIRS based data analysis, and evaluate the measurement's reliability across days., Methods: On three separate days (average days between visits 1 and 3: 19.4 ± 6.9 days), participants' (N = 15 males, 22 ± 2 yr.) post-occlusion reactive hyperemia (PORH) was measured in the left gastrocnemius muscle using Continuous-Wave NIRS (CW-NIRS). A blood pressure cuff was placed proximal to the knee and inflated to occlude lower leg blood flow for 5 min. The following CW-NIRS parameters were selected: (1) percent saturation in HbO 2 (StO 2 %) at baseline; (2) the O 2 Hb range used to normalize the NIRS signal; (3) the time for the O 2 Hb signal to reach 50 % peak post-occlusion hyperemia (T 1/2 ), and (4) the post peak hyperemic O 2 Hb recovery slope (O 2 REC-SLP). Absolute agreement between the two analysts was calculated using two-way random effects Intraclass Correlation Coefficients (ICC 2,1 ). Consistency between analysts and across days was calculated using two-way mixed models (ICC 3,1 ). Mean and 95 % confidence intervals (CI) of ICCs are reported. Coefficient of variation (CV) and standard error of the measurement (SEM) are reported., Results: The ICC 2,1 data indicated "adequate" to "excellent" absolute agreement between the two NIRS analysts. ICC 2,3 data indicated "adequate" to "good" reliability across visits. The CV and SEM for rater 1 and rater 2 across visit were StO 2 (CV: 3.79 % ± 2.71 % and 4.50 % ± 2.37 %; SEM: 3.42 and 3.82), O 2 Hb range (CV: 10.50 ± 5.93 and 12.79 ± 12.41; SEM: 3.26 and 4.71), T 1/2 (CV: 11.15 % ± 5.52 % and 10.96 % ± 4.50; SEM: 1.22 and 1.11), and O 2 REC-SLP (CV: 19.49 % ± 9.99 % and 18.45 % ± 9.48 %; SEM: 0.04 and 0.04)., Conclusion: It is concluded that NIRS parameters assessed show adequate reliability between analysts and across three visits. It is recommended, when feasible and because of the absence of 100 % reliability, that investigators employ more than one rater for scoring at least a portion of the data across each trial in a study's control condition in order to have the ability to estimate the magnitude of error attributable to imperfect reliability., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Co-author Dr. Kevin McCully is President of Infrared Rx a company that makes and offers tools to measure blood flow. The other authors declare no conflicts of interest, financial and all the authors on this manuscript contributed to this project., (Copyright © 2023. Published by Elsevier Inc.)

The body of research on exercise and physical activity among persons with multiple sclerosis(MS) has expanded rapidly in quantity, but not necessarily quality, over the past 20+ years. There is evidence for beneficial effects of exercise and physical activity on immune cells and neurotrophic factors, brain structure and function, walking and cognitive performance, fatigue, depression, and pain, and quality of life among persons with MS. Nevertheless, there is heterogeneity in the outcomes of exercise and physical activity, and a recognition of substantial challenges for improving the effectiveness of those behaviors in MS. To move the field forward, members of the National MS Society physical wellness research working-group pooled collective experiences for identifying challenges, logistic complexities, and opportunities for researchers in designing and conducting interventions of exercise and physical activity among persons with MS. We examined the scope of our experiences and identified collective "lessons learned" regarding the behaviors themselves; study design features and stage of research; study setting, safety, and sample selection; and implementation of randomized controlled trials(RCTs) and treatment fidelity. This paper provides a resource that can inform researchers, particularly new investigators or established investigators transitioning into MS, on conducting high-quality RCTs on exercise and physical activity in MS., Competing Interests: Declaration of Competing Interest The authors report no conflicts of interest regarding this paper, and there was no source of funding for this paper., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Purpose: Adopting and continuing physical activity (PA) is critical for the management of multiple sclerosis (MS). The role that spouses or partners play in the adoption and continuation of PA in women with MS has yet to be explored., Methods: Nine women with MS and their respective spouses volunteered for in-depth, semi-structured interviews that lasted approximately an hour. Interviews were transcribed and analyzed thematically. Spouse interview data were used to contextualize and provide a richer understanding of themes from women with MS., Results: Three themes were constructed from analysis of the interview data with women with MS: support, motivation to perform PA, and PA prior to MS. Support was most discussed and took the form joining in PA, supporting PA accomplishments or information sharing, assisting with PA, and encouraging separate PA. Motivation to perform PA and prior PA also were impacted by the women's spouses and their behaviors., Conclusions: This study points to the importance of support and perception of support by spouses for women with MS. Support was highly valued regardless of the form that it took. Women with MS could benefit from understanding and encouraging the various supporting roles spouses play in the decisions women with MS make to be physically active.IMPLICATIONS FOR REHABILITATIONWomen with MS and their spouses consider physical activity to be beneficial.Women with MS value the support their spouses provide to encourage them to be physically active.Women with MS can perceive support from their spouses in varying ways, including support in initiating physical activity, supporting physical activity accomplishments or information sharing, assisting with physical activity, and encouraging separate physical activity.Physical activity programming for this population should consider ways to incorporate spousal support.

The purpose of this article is to highlight the importance of considering sleep-disordered breathing (SDB) as a potential confounder to rehabilitation research interventions in spinal cord injury (SCI). SDB is highly prevalent in SCI, with increased prevalence in individuals with higher and more severe lesions, and the criterion standard treatment with continuous positive airway pressure remains problematic. Despite its high prevalence, SDB is often untested and untreated in individuals with SCI. In individuals without SCI, SDB is known to negatively affect physical function and many of the physiological systems that negatively affect physical rehabilitation in SCI. Thus, owing to the high prevalence, under testing, low treatment adherence, and known negative effect on the physical function, it is contended that underdiagnosed SDB in SCI may be confounding physical rehabilitation research studies in individuals with SCI. Studies investigating the effect of treating SDB and its effect on physical rehabilitation in SCI were unable to be located. Thus, studies investigating the likely integrated relationship among physical rehabilitation, SDB, and proper treatment of SDB in SCI are needed. Owing to rapid growth in both sleep medicine and physical rehabilitation intervention research in SCI, the authors contend it is the appropriate time to begin the conversations and collaborations between these fields. We discuss a general overview of SDB and physical training modalities, as well as how SDB could be affecting these studies., (Published by Elsevier Inc.)

The bone vascular system is important, yet evaluation of bone hemodynamics is difficult and expensive. This study evaluated the utility and reliability of near-infrared spectroscopy (NIRS), a portable and relatively inexpensive device, in measuring tibial hemodynamics and metabolic rate. Eleven participants were tested twice using post-occlusive reactive hyperemia technique with the NIRS probes placed on the tibia and the medial gastrocnemius (MG) muscle. Measurements were made at rest and after 2 levels of plantarflexion exercise. The difference between oxygenated and deoxygenated hemoglobin signal could be reliably measured with small coefficients of variation (CV; range 5.7-9.8%) and high intraclass correlation coefficients (ICC; range 0.73-0.91). Deoxygenated hemoglobin rate of change, a potential marker for bone metabolism, also showed good reliability (CV range 7.5-9.8%, ICC range 0.90-0.93). The tibia was characterized with a much slower metabolic rate compared with MG ( p  < 0.001). While exercise significantly increased MG metabolic rate in a dose-dependent manner (all p  < 0.05), no changes were observed for the tibia after exercise compared with rest (all p  > 0.05). NIRS is a suitable tool for monitoring hemodynamics and metabolism in the tibia. However, the local muscle exercise protocol utilized in the current study did not influence bone hemodynamics or metabolic rate. Novelty: NIRS can be used to monitor tibial hemodynamics and metabolism with good reliability. Short-duration local muscle exercise increased metabolic rate in muscle but not in bone. High level of loading and exercise volume may be needed to elicit measurable metabolic changes in bone.

Background: Non-invasive determination of mitochondrial capacity via near infrared spectroscopy (NIRS) typically involves voluntary exercise of a single muscle group followed by as many as 26 brief ischemic cuff occlusions to determine a single recovery rate constant (k)., Purpose: To determine the within- and between-visit repeatability of a shortened bilateral NIRS protocol, and to establish the feasibility of hamstring k measurements., Methods: Sixteen young (eight women, eight men; 22 ± 3 years) active adults underwent a bilateral electrical stimulation protocol in which multiple (n = 4) measurements of k for the vastus lateralis (VL) and medial hamstring (MH) muscles were determined on two visits. Repeatability (CV% and intraclass correlations, ICC) and equivalency across visits were assessed for both muscles., Results: Mean k values in the VL were consistent with published values and within-visit ICCs were moderately high for both muscles in both sexes. In men, average k values on visit 2 were within 1% (VL muscle) and 5% (MH muscle) of the values on visit 1 (all p > 0.78). In women, average k values were 10%-15% lower on visit 2 (p = 0.01 and p = 0.15 for MH and VL) with the largest between-visit differences in a subset of participants with the most days between visits., Conclusions: This bilateral NIRS protocol is time efficient and provides valid estimates of k in both sexes and muscle groups with acceptable within-visit repeatability. Lower than expected between-visit repeatability in some participants reinforces the need for further investigation of this newly developed protocol to identify and control for experimental and behavioral sources of variation., (© 2021 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

Diseases and associated fragility of bone is an important medical issue. There is increasing evidence that bone health is related to blood flow and oxygen delivery. The development of non-invasive methods to evaluate bone blood flow and oxygen delivery promise to improve the detection and treatment of bone health in human. Near-infrared spectroscopy (NIRS) has been used to evaluate oxygen levels, blood flow, and metabolism in skeletal muscle and brain. While the limited penetration depth of NIRS restricts its application, NIRS studies have been performed on the medial aspect of the tibia and some other prominent bone sites. Two approaches using NIRS to evaluate bone health are discussed: (1) the rate of re-oxygenation of bone after a short bout of ischemia, and (2) the dynamics of oxygen levels during an intervention such as resistance exercise. Early studies have shown these approaches to have the potential to evaluate bone vascular health as well as the predicted efficacy of an intervention before changes in bone composition are detectable. Future studies are needed to fully develop and exploit the use of NIRS technology for the study of bone health., Competing Interests: KM is the President of Infrared Rx, Inc., a NIRS software company. The remaining author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2020 Zhang and McCully.)

Endurance of the muscles of the neck are rarely studied. This study measured the endurance index (EI) of the sternocleidomastoid (SCM) and upper trapezius muscles of the neck (trap). The vastus lateralis (VL) was used for comparison. Skeletal muscle endurance of twelve healthy subjects, age 19-22 years, were tested on their SCM and trap in random order on one day, VL was tested on a separate day. Participants were tested in the supine position for the SCM and VL muscles and the prone position for the trap. Muscle contractions consisted of a 5 Hz twitch electrical stimulation for 5 min. Muscle acceleration (resultant vector) was measured using a triaxial accelerometer. EI was the ending acceleration as a percentage of the maximal acceleration. The endurance index (EI) for the SCM, trap, and VL was 42.3 ± 13.0%, 42.3 ± 20.2%, and 92.9 ± 11.0%, respectively. The EI of the VL was significantly higher than the EI of the SCM ( t (2,22) = 10.33, p < 0.001) and the trap ( t (2,22) = 7.625, p < 0.001). The EI was not different between the SCM and the trap muscle ( t (2,22) = 0.004, p = 0.997). In conclusion, the neck muscles had much less endurance than the muscles in the leg and could make fatigued athletes more susceptible to concussions caused by head impacts.

Objective: To assess the reliability and reproducibility of using a four arterial occlusions protocol and near-infrared spectroscopy (NIRS) to measure resting and post-exercise muscle oxidative metabolism (mVO 2 )., Approach: mVO 2 was measured on the forearm muscles on two different days (day1 and day2) within one week in 11 healthy young adults (24.2 ± 2.7 years; 5 males). mVO 2 was measured using NIRS during four repeated arterial occlusions at rest, and 5 min after exercise consisting of 90 s of rapid concentric contractions (5 minEPOC)., Main Results: Resting mVO 2 with four measurements was 17.88 ± 3.04% min -1 on day 1 and 19.42 ± 3.03% min -1 on day 2 (p = 0.171) with a coefficient of variation (CV) of 10.1%. When using only the first measurement, the CV increased to 18.5% (p = 0.039). 5minEPOC was 212.4 ± 142.5% and 177.1 ± 125.8% higher than resting and was not different between days one and two (53.83 ± 21.17% min -1 and 52.22 ± 22.10% min -1 , respectively, p= 0.199). The CV and intraclass correlation (ICC) for 5minEPOC between days one and two were, 6.5% and 0.98, respectively. Using only the first value for 5minEPOC resulted in slightly higher CV but similar ICC (7.6% and 0.98, respectively; both p > 0.05)., Significance: Our results suggest that within a single testing session, one arterial occlusion can provide reproducible measurements for both resting and post-exercise mVO 2 similar to that of a four arterial occlusions protocol. While a four arterial occlusion protocol provides similar reliability for post-exercise mVO 2 with one arterial occlusion, it reduces the day-to-day variance for resting mVO 2 and therefore should be employed for longitudinal studies.

Aim: Few studies have addressed impact of participation in exercise programs on caregivers or family members of individuals with disabilities. Purpose: To evaluate the impact of interaction rich wellness program on family members or caregivers of participants. Methods: Nine family members or caregivers were selected for interviews. Interviews were transcribed and analyzed using a thematic approach. Results: Five themes were constructed from analysis of the interview data: benefit of class to self, positive feelings about participation, relationship dynamic, importance of classroom interaction, and burden of class. The first four themes occurred in caregivers despite individual burden determined by self-reported interview scores on the Zarit Burden interview. Conclusion: This study demonstrated the impact of an interaction rich exercise program on wellness of participants with disabilities and respective caregivers or family members. Caregivers or family members do acknowledge benefits of the program to themselves. However, the program does not reduce caregiver burden.Implications for RehabilitationRehabilitation professionals should be cognizant of the potential for indirect benefit of rehabilitation or exercise programs on family members or caregivers of patients.Rehabilitation programs should consider the indirect benefit on the caregivers of patients when evaluating the burden of a program on caregivers.Rehabilitation professionals should focus on interpersonal interaction to aid in positive outcomes for both patients and caregivers.

Background: Near-infrared spectroscopy (NIRS) has been used to measure muscle mitochondrial capacity (mVO 2 max) as the recovery rate constant of muscle metabolism after exercise. The current method requires as many as 50 short ischemic occlusions to generate two recovery rate constants., Purpose: To determine the validity and repeatability of using a 6-occlusion protocol versus one with 22 occlusions to measure muscle mitochondrial capacity. The order effect of performing multiple Mito6 test was also evaluated., Method: In two independent data sets (bicep n = 7, forearm A n = 23), recovery curves were analyzed independently using both the 6 and 22 occlusion methods. A third data set (forearm B n = 16) was generated on the forearm muscles of healthy subjects using four 6-occlusion tests performed in succession. Recovery rate constants were generated using a MATLAB routine., Results: When calculated from the same data set, the recovery rate constants were not significantly different between the 22 occlusion and 6 occlusion methods for the bicep (1.43 ± 0.33 min -1 , 1.43 ± 0.35 min -1 , p = 0.81) and the forearm A (1.97 ± 0.40 min -1 , 1.97 ± 0.43 min -1 , p = 0.90). Equivalence testing showed that the mean difference was not different than zero and the 90% confidence intervals were within 5% of the average rate constant. This was true for the Mito6 and the Mito5 ∗ approaches. Bland-Altman analysis showed a slope of 0.21 min -1 and an r of 0.045 for the bicep dataset and a slope of -0.01 min -1 and an r of 0.045 for the forearm A dataset. When performing the four 6-occlusion tests; recovery rate constants showed no order effects (1.50 ± 0.51 min -1 , 1.42 ± 0.54 min -1 , 1.26 ± 0.41 min -1 , 1.29 ± 0.47 min -1 , P > 0.05)., Conclusion: The Mito6 analysis is a valid and repeatable approach to measure mitochondrial capacity. The Mito6 protocol used fewer ischemic occlusion periods and multiple tests could be performed in succession in less time, increasing the practicality of the NIRS mitochondrial capacity test. There were no order effects for the rate constants of four repeated 6-occlusion tests of mitochondrial capacity, supporting the use of multiple tests to improve accuracy., (Copyright © 2020 Sumner, Beard, Pryor, Das and McCully.)

The impact of type 1 diabetes (T1D) on muscle endurance and oxidative capacity is currently unknown., Purpose: Measure muscle endurance and oxidative capacity of adults with T1D compared to controls., Methods: A cross-sectional study design with a control group was used. Subjects (19-37 years old) with T1D (n=17) and controls (n=17) were assessed with hemoglobin A1c (HbA1c) and casual glucose. Muscle endurance was measured with an accelerometer at stimulation frequencies of 2, 4, and 6 Hz for a total of nine minutes. Mitochondrial capacity was measured using near-infrared spectroscopy after exercise as the rate constant of the rate of recovery of oxygen consumption., Results: T1D and control groups were similar in age, sex, height, and race. The T1D group had slightly higher BMI values and adipose tissue thickness over the forearm muscles. Casual glucose was 150±70 mg/dL for T1D and 98±16 mg/dL for controls (P=0.006). HbA1c of T1D subjects was 7.1±0.9% and 5.0±0.4% for controls (P<0.01). Endurance indexes at 2, 4, and 6 Hz were 94.5±5.2%, 81.8±8.4%, and 68.6±13.5% for T1D and 94.6±4.1%, 85.9±6.3%, and 68.7±15.4% for controls (p = 0.97, 0.12, 0.99, respectively). There were no differences between groups in mitochondrial capacity (T1D= 1.9±0.5 min -1 and control=1.8±0.4 min -1 , P=0.29) or reperfusion rate (T1D= 8.8±2.8s and control=10.3±3.0s, P=0.88). There were no significant correlations between HbA1c and either muscle endurance, mitochondrial capacity or reperfusion rate., Conclusions: Adults with T1D did not have reduced oxidative capacity, muscle endurance or muscle reperfusion rates compared to controls. HbA1c also did not correlate with muscle endurance, mitochondrial capacity or reperfusion rates. Future studies should extend these measurements to older people or people with poorly-controlled T1D., Competing Interests: Conflict of interest One of the authors, Kevin McCully, is the President and Chief Science Officer of Infrared Rx, Inc, a company that develop analysis software related to the NIRS measurements

Near-Infrared Spectroscopy (NIRS) has been used to measure muscle mitochondrial capacity (mVO2max) as the recovery rate constant of muscle metabolism after exercise. The current method requires as many as 50 short ischemic occlusions to generate 2 recovery rate constants., Purpose: To determine the effectiveness of using a 6-occlusion protocol (Mito6) versus one with 22 occlusions (Mito22) to measure muscle mitochondrial capacity., Method: In two independent data sets (bicep n=7, forearm A n=23), recovery curves were analyzed independently using both the Mito6 and Mito22 analyses. A third data set (Forearm B, n=16) was generated on forearm muscles of healthy subjects using four Mito6 tests performed in succession. Recovery rate constants were generated using a MATLAB routine., Results: When calculated from the same data set, the recovery rate constants were not significantly different between the Mito22 and Mito6 analyses for the bicep (1.43+0.33min-1, 1.43+0.35min-1, p=0.81) and the forearm A (1.97+0.40min-1, 1.97+0.43min-1, p=0.90). The correlation between Mito22 and Mito6 recovery rate constants was y=1.07x-0.09, R2=0.90 for the bicep data and 1.00x+0.01, R2=0.85 for the forearm A data. When performing the four Mito6 tests in the Forearm B study; recovery rate constants were not different between tests (1.50±0.51 min-1, 1.42±0.54 min-1, 1.26±0.41 min-1, 1.29±0.47 min-1, P>0.05)., Conclusions: Muscle mitochondrial capacity was not different between the Mito6 analysis and the longer Mito22 analysis. The Mito6 protocol was considered more practical as it used fewer ischemic occlusion periods, and multiple tests could be performed in succession in less time. There were no order effects for the rate constants of four repeated Mito6 tests of mitochondrial capacity, supporting the use of multiple tests to improve accuracy.

The benefits of exercise for smokers attempting to quit are partially dependent on physical activity levels prior to cessation. Mood disturbances can manifest within 30 min of smoking a cigarette and contribute to negative reinforcement of smoking behavior over time, whereas a single bout of aerobic exercise can reduce negative mood states and improve affect on a similar timescale in non-smokers. The acute effects of exercise among non-abstaining smokers immediately after a cigarette are unknown but may have clinical implications for smokers considering cessation. The aim of this study was to examine the concurrent effects of exercise on mood disturbance and prefrontal brain hemodynamic response to emotionally arousing scenes 30 min after smoking a cigarette and to test whether prefrontal brain hemodynamic response was correlated with affective ratings of the scenes. Fifteen cigarette smokers, averaging 47.6 cigarettes/week in the year prior to screening, served as participants. Functional near-infrared spectroscopy was used to measure hemodynamic status over the dorsolateral prefrontal cortex (DLPFC). Participants viewed pleasant, unpleasant, and neutral scenes prior to smoking a cigarette and 30 min later after seated rest or exercise at a preferred intensity. Mood disturbance was assessed by the Profile of Mood States-Brief Form four times: before smoking a cigarette, before and after exercise and rest, and after a post-condition (exercise/rest) exposure to emotionally arousing scenes. Compared to seated rest, cycling after a cigarette reduced mood disturbance (p = =.038) and DLPFC hemodynamic response to unpleasant (p = =.003) and pleasant (p = =.021) scenes relative to neutral scenes. DLPFC hemodynamic response was not related to affective ratings of scenes. We report that cycling for 20 min at a preferred intensity reduces mood disturbances which occur shortly after smoking a cigarette and blunts DLPFC hemodynamic response to emotionally arousing scenes. The findings encourage further investigation of exercise for smokers in the maintenance stage of smoking cessation., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Increasing muscle length (passive stretch) has been shown to reduce muscle oxygen levels by increasing intramuscular pressure., Purpose: To measure the effect of passive stretch on muscle-specific endurance and oxygen saturation in the vastus lateralis and medial gastrocnemius muscle groups., Methods: Muscle Endurance (EI), Muscle blood flow (MBF), and Muscle oxygen saturation (MVO 2 ) were measured on the vastus lateralis and medial gastrocnemius muscles in a passive stretched (lengthened) and relaxed (shortened) positions in 10 healthy individuals (21 ± 1 yrs.). Muscle endurance was measured with tri-axial accelerometer. Muscle oxygen saturation and blood flow were measured using a continuous wavelength Near Infrared Spectroscopy (NIRS)., Results: Muscle at stretched position showed a lower endurance index in the gastrocnemius (51 ± 9.6% versus 77 ± 9.1%, p = 0.008) and vastus lateralis (54 ± 8.9% versus 75 ± 9.6%, p < 0.001). The time to half recovery of oxygen levels during reactive hyperemia was slower in the stretched positions for the gastrocnemius (11.4 ± 1.0 s versus 8.2 ± 1.1 s, p < 0.001) and the vastus lateralis (9.8 ± 1.9 s versus 6.3 ± 0.7 s, p < 0.001). However, oxygen saturation during the endurance tests were not different between stretched and relaxed conditions in both muscle (p > 0.05 for all comparisons)., Conclusions: Studies of muscle endurance need to control for muscle length as changes in muscle length can influence muscle endurance., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Near-infrared spectroscopy (NIRS) has become an increasingly valuable tool to monitor tissue oxygenation (T oxy ) in vivo. Observations of changes in the absorption of light with T oxy have been recognized as early as 1876, leading to a milestone NIRS paper by Jöbsis in 1977. Changes in the absorption and scatting of light in the 700-850-nm range has been successfully used to evaluate T oxy . The most practical devices use continuous-wave light providing relative values of T oxy . Phase-modulated or pulsed light can monitor both absorption and scattering providing more accurate signals. NIRS provides excellent time resolution (~ 10 Hz), and multiple source-detector pairs can be used to provide low-resolution imaging. NIRS has been applied to a wide range of populations. Continued development of NIRS devices in terms of lower cost, better detection of both absorption and scattering, and smaller size will lead to a promising future for NIRS studies.

Background: Recent evidence suggests that skeletal muscle dysfunction is involved in disability progression in people with multiple sclerosis (MS). However, the relationship between muscle dysfunction and walking impairments in MS remains unclear. Thus, the cross-sectional relationships between muscle-specific oxidative capacity and walking endurance in women with MS were evaluated., Methods: Twenty women with MS (11 African American, 9 white) were tested. Muscle oxidative capacity of the medial gastrocnemius was measured using near-infrared spectroscopy after electrical stimulation. Muscle endurance was evaluated using accelerometer-based mechanomyography during electrical stimulation. Muscle strength was measured during maximal voluntary plantarflexion using handheld dynamometry. Walking function was measured using the Timed 25-Foot Walk test and the 6-Minute Walk Test (6MWT)., Results: Reduced muscle oxidative capacity ( R 2 = 0.68-0.71, P < .01) and muscle endurance ( R 2 = 0.59-0.78, P < .01) were associated with lower Timed 25-Foot Walk time and 6MWT distance. Muscle strength was weakly correlated to 6MWT distance ( R 2 = 0.21, P = .02). No differences in muscle function or clinical outcome measures were found between African American and white subgroups. Women with moderate-to-severe disability (Expanded Disability Status Scale [EDSS] score, 5.0-6.5) had significantly reduced muscle oxidative capacity, muscle endurance, and walking ability compared with women with mild disability (EDSS score, 2.5-4.5)., Conclusions: Reductions in muscle function in people with MS are related to declines in walking function across all levels of disability. Muscle dysfunction is not differentially related to walking impairment in African American and white women with MS., Competing Interests: Dr. McCully is the president of Infrared Rx. The other authors declare no conflicts of interest., (© 2019 Consortium of Multiple Sclerosis Centers.)

Purpose: The recovery of muscle oxygen consumption (m[Formula: see text]O 2 ) after exercise provides a measure of skeletal muscle mitochondrial capacity, as more and better-functioning mitochondria will be able to restore m[Formula: see text]O 2 faster to the pre-exercise state. The aim was to measure muscle mitochondrial capacity using near-infrared spectroscopy (NIRS) within a healthy, normally active population and relate this to parameters of aerobic fitness, investigating the applicability and relevance of using NIRS to assess muscle mitochondrial capacity non-invasively., Methods: Mitochondrial capacity was analysed in the gastrocnemius and flexor digitorum superficialis (FDS) muscles of eight relatively high-aerobic fitness ([Formula: see text]O 2 peak ≥ 57 mL/kg/min) and eight relatively low-aerobic fitness male subjects ([Formula: see text]O 2 peak ≤ 47 mL/kg/min). Recovery of whole body [Formula: see text]O 2 , i.e. excess post-exercise oxygen consumption (EPOC) was analysed after a cycling protocol., Results: Mitochondrial capacity, as analysed using NIRS, was significantly higher in high-fitness individuals compared to low-fitness individuals in the gastrocnemius, but not in the FDS (p = 0.0036 and p = 0.20, respectively). Mitochondrial capacity in the gastrocnemius was significantly correlated with [Formula: see text]O 2 peak (R 2  = 0.57, p = 0.0019). Whole body [Formula: see text]O 2 recovery was significantly faster in the high-fitness individuals (p = 0.0048), and correlated significantly with mitochondrial capacity in the gastrocnemius (R 2  = 0.34, p = 0.028)., Conclusion: NIRS measurements can be used to assess differences in mitochondrial muscle oxygen consumption within a relatively normal, healthy population. Furthermore, mitochondrial capacity correlated with parameters of aerobic fitness ([Formula: see text]O 2 peak and EPOC), emphasising the physiological relevance of the NIRS measurements.

Purpose: This study examined the effects of repeated long-duration hyperoxic water immersions (WIs) at 1.35 atmospheres absolute (ATA) on neuromuscular endurance performance. We hypothesized that over a 5-day period of consecutive, resting, long-duration hyperoxic WIs there would be a decrease to neuromuscular endurance performance and tissue oxygenation with the quadriceps muscle, but not with the forearm flexors., Methods: Thirteen well-trained, male subjects completed five consecutive 6-h resting WIs with 18-h surface intervals during the dive week while breathing 100% oxygen at 1.35 ATA. We assessed skeletal muscle endurance performance before and after each WI, and 24 and 72 h after the final WI. Muscular endurance assessments included 40% maximal handgrip endurance (MHE) and 50-repetition maximal isokinetic (IK) knee extensions. Near-infrared spectroscopy (NIRS) was used to measure muscle oxidative capacity (MOC) of the vastus lateralis and localized muscle tissue oxygenation of the vastus lateralis and flexor carpi radialis. Simultaneously, we measured brachioradialis neuromuscular activation by surface electromyography (SEMG)., Results: MHE time-to-fatigue performance declined by 15% at WI 3 ( p = 0.009) and by 17% on WI 5 ( p = 0.002). Performance continued to decline by 22% at 24-h post-WI ( p < 0.001) and by 12% on 72-h post-WI ( p = 0.019). Fifty-repetition IK knee extension total work decreased by 5% ( p = 0.002) on WI 3, and was further reduced by 7.5 and 12.3% ( p = 0.032) at pre-WI 5 and 24-h post-WI, respectively. However, the rate of fatigue was 8 ( p = 0.033) and 30% ( p = 0.017) lower at WI 3 and 24-h post-WI when compared to WI 1, respectively, demonstrating the muscles were still fatigued from the previous hyperoxic WIs. We detected no significant limitations in oxygen off-loading kinetics during the exercise or MOC measurements., Conclusion: Repeated, resting, long-duration hyperoxic WIs caused significant reductions to muscular endurance but not to indirect measures of oxygen kinetics in load bearing and non-load bearing muscles.

Background: Exercise can improve muscle function and mobility in people with multiple sclerosis (MS). However, the effects of exercise training on skeletal muscle oxidative capacity and endurance in people with MS remain unclear, and few studies have evaluated muscle plasticity in people with MS who have moderate-to-severe disability. The present study evaluated the effects of treadmill training on muscle oxidative capacity and muscle endurance and examined the relationship to walking function in people with MS who have moderate-to-severe disability., Methods: Six adults (mean ± SD age, 50 ± 4.9 years) with MS (Expanded Disability Status Scale score, 6.0-6.5) performed treadmill training for 24 minutes approximately twice per week for approximately 8 weeks (16 sessions total) using an antigravity treadmill system. The following measures were taken before and after the intervention phase: muscle oxidative capacity in the medial gastrocnemius using near-infrared spectroscopy after 15 to 20 seconds of electrical stimulation; muscle endurance in the medial gastrocnemius using accelerometer-based mechanomyography during 9 minutes of twitch electrical stimulation in three stages (3 minutes per stage) of increasing frequency (2, 4, and 6 Hz); and walking function using the 2-Minute Walk Test., Results: Mean ± SD muscle oxidative capacity increased from 0.64 ± 0.19 min -1 to 1.08 ± 0.52 min -1 (68.2%). Mean ± SD muscle endurance increased from 80.9% ± 15.2% to 91.5% ± 4.8% at 2 Hz, from 56.3% ± 20.1% to 76.6% ± 15.8% at 4 Hz, and from 29.2% ± 13.1% to 53.9% ± 19.4% at 6 Hz of stimulation in the gastrocnemius. There were no significant improvements in walking function., Conclusions: Treadmill training can improve muscle oxidative capacity and endurance in people with MS who have moderate-to-severe levels of disability., Competing Interests: Dr. McCully is the president of Infrared RX. The other authors declare no conflicts of interest.

Background: We propose a Phase III trial that compares the effectiveness of an exercise training program delivered in a facility-based setting with direct, in-person supervision or a home-based setting with remote supervision via telerehabilitation for improving walking performance in persons with multiple sclerosis(MS) who have walking dysfunction and mobility disability., Methods/design: The study was developed with stakeholder engagement and is a multi-site trial that follows a 2-stage, randomized choice design. The trial compares the effectiveness of a 16-week evidence-based, individualized exercise program delivered in a supervised, facility-based setting versus a remotely coached/guided, home-based setting using telerehabilitation in physically inactive and cognitively intact people with MS who have walking dysfunction and mobility disability(N = 500). The primary outcome is walking speed. The secondary outcomes are walking endurance, disability status, and patient-reported outcomes of physical activity, walking impairment, fatigue, and quality of life. The components of the exercise program itself are similar between the groups and follow the Guidelines for Exercise in MS protocol. This includes a program manual, exercise prescription, exercise equipment, social-cognitive theory materials including newsletters, logs, and calendars, and one-on-one behavioral coaching by exercise specialists with background in MS. The main difference between groups is the coaching approach and setting for delivering the exercise training program. The outcomes will be collected by treatment-blinded assessors at baseline(week 0), mid-intervention(week 8), post-intervention(week 16), and follow-up(week 52)., Discussion: The proposed study will provide evidence for the effectiveness of a novel, widely-scalable program for delivering exercise training in persons with MS who have walking dysfunction and mobility disability., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Near-infrared spectroscopy (NIRS) has been used to measure oxidative capacity, but regional differences have not been identified. Piano players are also a novel group of subjects for this lab., Methods: Controls ( n = 13) and piano players ( n = 8) were tested in a seated position on the right forearm. A fatigue test was performed for three minutes at 2, 4 and 6 Hz using electrical stimulation, which created an endurance index (EI) as the forearm fatigued. A six-cuff oxidative capacity test was performed using manual exercise to activate the muscle and allow for regional specificity. A rate constant (Rc) was generated from the mitochondrial capacity data., Results: Overall, piano players (Rc = 1.76 ± 0.6) and controls (Rc = 1.17 ± 0.3) have significant differences for the last two fingers ( p = 0.01). While controls have significant differences between the index (Rc = 1.86 ± 0.5) and last two fingers (Rc = 1.17 ± 0.3) ( p = 0.001), this difference was not observed in piano players. Overall, piano players (EI = 75.7 ± 12.3) and controls (EI = 73.0 ± 17.3) had no differences in endurance index values ( p = 0.71)., Conclusions: Piano players have significant differences in the mitochondrial capacity of the finger flexors that control the last two fingers compared to controls. The lack of difference between groups in the index fingers and overall endurance test suggests playing the piano produces training adaptations to the finger flexor muscles of the last two digits, which are rarely used by control subjects.

Near-infrared spectroscopy (NIRS) uses the relative absorption of light at 850 and 760 nm to determine skeletal muscle oxygen saturation. Previous studies have used the ratio of both signals to report muscle oxygen saturation., Purpose: The purpose of this pilot study is to assess the different approaches used to represent muscle oxygen saturation and to evaluate the pulsations of oxygenated hemoglobin/myoglobin (O 2 heme) and deoxygenated hemoglobin/myoglobin (Heme) signals., Method: Twelve participants, aged 20-29 years, were tested on the forearm flexor muscles using continuous-wave NIRS at rest. Measurements were taken during 2-3 min rest, physiological calibration (5 min ischemia), and reperfusion. Ten participants were included in the study analysis., Results: There was a significant difference in pulse size between O 2 heme and Heme signals at the three locations ( p < 0.05). Resting oxygen saturation was 58.8% + 9.2%, 69.6% + 3.9%, and 89.2% + 6.9% when calibrated using O 2 heme, the tissue oxygenation/saturation index (TSI), and Heme, respectively., Conclusion: The difference in magnitude of O 2 heme and Heme pulses with each heartbeat might suggest different anatomical locations of these signals, for which calibrating with just one of the signals instead of the ratio of both is proposed. Calculations of physiological calibration must account for increased blood volume in the tissue because of the changes in blood volume, which appear to be primarily from the O 2 heme signal. Resting oxygen levels calibrated with Heme agree with theoretical oxygen saturation.

Background: For individuals with disabilities, adherence and participation in wellness programs is a challenge. Adherence and participation were explored in a wellness class for people with disabilities., Objective: Understand what factors impact participant adherence and participation in the wellness class., Methods: Eight wellness class participants, who have been in the class for 6 to 36 months, were chosen for qualitative interviews. Interview responses were coded and analyzed for overarching themes., Results: A total of 77 codes were obtained from interview data. The primary theme identified from the codes was related to social interaction with the student-trainers, divided into subthemes of social accountability, motivation, supporting classroom environment, and participant-student interaction., Conclusion: The primary factor influencing adherence and participation was related to social interaction with student-trainers. These results suggest that social interaction can play a major role in continued participation in exercise as well as exercise adherence., Competing Interests: Declaration of conflicting interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2019.)

Rationale: Supervised treadmill exercise for claudication in peripheral arterial disease is effective but poorly tolerated because of ischemic leg pain. Near infrared spectroscopy allows non-invasive detection of muscle ischemia during exercise, allowing for characterization of tissue perfusion and oxygen utilization during training., Objective: We evaluated walking time, muscle blood flow, and muscle mitochondrial capacity in patients with peripheral artery disease after a traditional pain-based walking program and after a muscle oxygen-guided walking program., Method and Results: Patients with peripheral artery disease trained thrice weekly in 40-minute-long sessions for 12 weeks, randomized to oxygen-guided training ( n = 8, age 72 ± 9.7 years, 25% female) versus traditional pain-based training ( n = 10, age 71.6 ± 8.8 years, 20% female). Oxygen-guided training intensity was determined by maintaining a 15% reduction in skeletal muscle oxygenation by near infrared spectroscopy rather than relying on symptoms of pain to determine exercise effort. Pain free and maximal walking times were measured with a 12-minute Gardner treadmill test. Gastrocnemius mitochondrial capacity and blood flow were measured using near infrared spectroscopy. Baseline pain-free walking time was similar on a Gardner treadmill test (2.5 ± 0.9 vs. 3.6 ± 1.0 min, p = 0.5). After training, oxygen-guided cohorts improved similar to pain-guided cohorts (pain-free walking time 6.7 ± 0.9 vs. 6.9 ± 1.1 min, p < 0.01 for change from baseline and p = 0.97 between cohorts). Mitochondrial capacity improved in both groups but more so in the pain-guided cohort than in the oxygen-guided cohort (38.8 ± 8.3 vs. 14.0 ± 9.3, p = 0.018). Resting muscle blood flow did not improve significantly in either group with training., Conclusions: Oxygen-guided exercise training improves claudication comparable to pain-based training regimens. Adaptations in mitochondrial function rather than increases in limb perfusion may account for functional improvement. Increases in mitochondrial oxidative capacity may be proportional to the degree of tissue hypoxia during exercise.

Lower back pain is a common symptom potentially associated with skeletal muscle dysfunction. The purpose of this study was to evaluate endurance in the lower back muscles of healthy participants using accelerometer-based mechanomyography. Methods: Young healthy subjects (N = 7) were tested. Surface electrodes and a tri-axial accelerometer were placed over the erector spinae muscle along the T11-L1 Vertebrae. Stimulation was for 3 min each at 2, 4, and 6 Hz, and changes in acceleration were used to calculate an endurance index (EI). Reproducibility of the endurance index measurements was tested on two separate days. Wrist flexor and vastus lateralis muscles were tested for comparison. Near Infrared Spectroscopy (NIRS) was used to measure muscle oxygen levels (O 2 Hb) (N = 5). EI was 70.3 + 13.4, 32.6 + 8.4, and 19.2 + 6.2% for 2, 4, 6 Hz, respectively. The coefficients of variation were 9.8, 13.9, and 20.3% for 2, 4, 6 Hz, respectively. EI values were lower in the erector spinae muscles compared to the arm and the leg ( p < 0.05). O 2 Hb values were 86.4 + 10.9% at rest and were 77.2 + 15.5, 84.3 + 14.1, and 84.1 + 18.9% for 2, 4, 6 Hz, respectively ( p > 0.05, all comparisons). An endurance index can be obtained from the lower back erectors muscles that is reproducible and not influenced by voluntary effort or muscle oxygen levels.

Background: As the knee joint is a common site for injury among younger people, the purpose of this study was to measure the skeletal muscle endurance and strength on people with prior anterior cruciate ligament (ACL) knee reconstruction surgery., Method: Young healthy female subjects who reported having knee reconstruction surgery more than one-year prior were tested. The skeletal muscle endurance index (EI) of the hamstrings and quadriceps muscles was determined as the decline in the specific muscle acceleration in response to 2 Hz, 4 Hz, and 6 Hz electrical stimulation. Maximal isometric muscle strength (MVC) was measured in the hamstrings and quadriceps muscles., Results: The hamstrings muscles in the injured leg had less endurance than the non-injured leg at 6 Hz stimulation (55.5 ± 13.2% versus 78.0 ± 13.3%, p < 0.01). Muscle endurance was not reduced in the quadriceps muscles in the injured leg compared to the non-injured leg at 6 Hz stimulation (78.0 ± 13.3% versus 80.3 ± 10.0%, p = 0.45). There were no differences in MVC between the injured and non-injured legs for either the hamstrings ( p = 0.20) or quadriceps muscles ( p = 0.67)., Conclusions: Muscle endurance was reduced in the hamstrings muscles at least one-year post injury, while hamstrings strength was recovered. Reduced hamstrings muscle endurance could be a result of lack of endurance training during rehabilitation. This may contribute to re-injury in the muscle, even in people who have recovered muscle strength.

Context: Hypotension that occurs after a single bout of aerobic exercise also attenuates the vascular response to discrete stressors, an effect that can last for hours. It is unknown whether the hypotensive benefits of traditional exercise extend to alternative forms of mindful exercise, such as yoga, to confer transient protection against neurovascular challenges that increase blood pressure (BP)., Objectives: The study intended to examine the effects of acute exercise on neurovascular responses to exposure of the forehead of female yoga practitioners to vasoconstrictive cold (ie, to cold pressor stress)., Design: The research team designed a study with 3 conditions (ie, with participants' participation in 3 activities on separate days in a repeated-measures design). Participants were randomly assigned to perform the activities in 1 of 3 orders across successive visits., Participants: Participants were 9 females, 20 to 33 y old, who had regularly practiced Hatha yoga from 6 mo to 12 y before the start of the study. All participants were normotensive at entry to the study and had normal body weights for their heights., Interventions: All participants performed 3 activities: (1) self-directed yoga practice, the intervention; (2) cycling exercise at a self-selected intensity, a positive control; and (3) quiet rest, a negative control., Outcome Measures: Postintervention, participants' foreheads were exposed to cold. Their systolic blood pressures (SBPs), diastolic blood pressures (DBPs), pulse rates, and forearm oxygenation were assessed using near-infrared spectroscopy., Results: Participants' SBPs and DBPs increased during cold pressor stress under all conditions, concurrent with decreased forearm oxygenation. During recovery from the cold, participants' BPs declined to near precold pressor baseline levels after yoga and cycling but remained elevated after quiet rest., Conclusions: The enhanced recovery of BP from cold applied to the forehead after yoga practice or cycling exercise suggests that both types of exercise promote a hypotensive response, which could indicate lowered cardiovascular risk.

Background: Symptoms of fatigue and pain are often reported for the trapezius muscle in the shoulder. The present study evaluated endurance in the trapezius muscles of healthy participants using electric twitch mechanomyography (ETM)., Methods: Surface electrodes and a tri-axial accelerometer were placed over the left trapezius muscle. Muscles were stimulated for 3 min each at 2 Hz, 4 Hz and 6 Hz. Maintenance of acceleration during muscle twitches was used to calculate an endurance index (EI). Subjects (n = 9) were tested on two separate days to assess reproducibility of the trapezius EI measurements. The endurance measurements were made on the wrist flexor and vastus lateralis muscles for comparison. Near infrared spectroscopy was used to measure muscle oxygenation (HbO 2 ) during the stimulation protocol (n = 8)., Results: Mean (SD) EI was 84.9% (8.7%), 63.3% (19.1%) and 41.7% (20.0%) for 2 Hz, 4 Hz and 6 Hz, respectively. The coefficients of variation were 7.4%, 11.3% and 24.0% for 2 Hz, 4 Hz and 6 Hz, respectively. EI values were significantly lower in the trapezius compared to arm and leg muscles (p < 0.05). HbO 2 values were unchanged from resting values with electrical stimulation., Conclusions: The EI as measured by ETM may provide a reproducible method of evaluating function in trapezius muscles that is not influenced by oxygen saturation.

Background: People with multiple sclerosis (MS) have identified "wellness" and associated behaviors as a high priority based on "social media listening" undertaken by the National MS Society (i.e. the Society)., Objective: The Society recently convened a group that consisted of researchers with experience in MS and wellness-related research, Society staff members, and an individual with MS for developing recommendations regarding a wellness research agenda., Method: The members of the group engaged in focal reviews and discussions involving the state of science within three approaches for promoting wellness in MS, namely diet, exercise, and emotional wellness., Results: That process informed a group-mediated activity for developing and prioritizing research goals for wellness in MS. This served as a background for articulating the mission and objectives of the Society's Wellness Research Working Group., Conclusion: The primary mission of the Wellness Research Working Group is the provision of scientific evidence supporting the application of lifestyle, behavioral, and psychosocial approaches for promoting optimal health of mind, body, and spirit (i.e. wellness) in people with MS as well as managing the disease and its consequences.

Introduction: In this study we noninvasively evaluated skeletal muscle mitochondrial capacity, muscle-specific endurance, and energy/fatigue feelings in persons with Friedreich ataxia (FRDA) and able-bodied controls (AB)., Methods: Forearm mitochondrial capacity was measured in FRDA (n = 16) and AB (n = 10) study participants using the rate of recovery of oxygen consumption after electrical stimulation with near-infrared spectroscopy. Mechanomyography (MMG) assessed muscle endurance after electrical stimulation for 3 minutes at 2 Hz, 4 Hz, and 6 Hz. Validated scales assessed disease severity and energy/fatigue feelings., Results: Groups did not differ in mitochondrial capacity (FRDA and AB: 1.8 ± 0.3 L/min). The difference in muscle endurance at 6 Hz was lower by 19.2% in the FRDA group (group effect: P < 0.001). Feelings of physical energy were 34% lower in FRDA group. In FDRA muscle, endurance was positively related to mitochondrial capacity (r = 0.59, P = 0.03), and disease severity was negatively related to mitochondrial capacity (r = -0.55, P = 0.04) and muscle endurance (r = -0.60, P = 0.01)., Conclusion: Non-invasive measures of skeletal muscle mitochondrial capacity and muscle-specific endurance are useful in monitoring FRDA. Muscle Nerve 56: 773-779, 2017., (© 2017 Wiley Periodicals, Inc.)

We discuss a novel hypothesis: the effect size of postmeal exercise for attenuating postprandial glucose will be a function of the exercise bout vs. the size of the postprandial glucose response, specifically peak and duration of the postprandial glucose excursion.

The ability to sustain submaximal exercise is largely dependent on the oxidative capacity of mitochondria within skeletal muscle, and impairments in oxidative metabolism have been implicated in many neurologic and cardiovascular pathologies. Here we review studies which have demonstrated the utility of Near-infrared spectroscopy (NIRS) as a method of evaluating of skeletal muscle mitochondrial dysfunction in clinical human populations. NIRS has been previously used to noninvasively measure tissue oxygen saturation, but recent studies have demonstrated the utility of NIRS as a method of evaluating skeletal muscle oxidative capacity using post-exercise recovery kinetics of oxygen metabolism. In comparison to historical methods of measuring muscle metabolic dysfunction in vivo , NIRS provides a more versatile and economical method of evaluating mitochondrial oxidative capacity in humans. These advantages generate great potential for the clinical applicability of NIRS as a means of evaluating muscle dysfunction in clinical populations.

Acute exercise-induced inflammation is implicated in mediating the beneficial adaptations to regular exercise. Evidence suggests that reduced oxygen and/or blood flow to contracting muscle alters cytokine appearance. However, the acute inflammatory responses to hypoxic/ischemic exercise have been documented with inconsistent results and may not accurately reflect the ischemia produced during exercise in patients with ischemic cardiovascular diseases. Therefore, we determined the extent to which local inflammation is involved in the response to ischemic exercise. Fourteen healthy males performed unilateral isometric forearm contractions for 30 min with and without experimental ischemia. Blood was drawn at baseline, 5 and 10 min into exercise, at the end of exercise, and 30, 60, and 120 min after exercise. Oxygen saturation levels, as measured by near-infrared spectroscopy, were reduced by 10% and 41% during nonischemic and ischemic exercise, respectively. Nonischemic exercise did not affect cytokine values. Ischemia enhanced concentrations of basic fibroblast growth factor, interleukin (IL)-6, IL-10, tumor necrosis factor-alpha, and vascular endothelial growth factor during exercise, but IL-8 was not influenced by ischemic exercise. In conclusion, the present study demonstrates that ischemic, small-muscle endurance exercise elicits local inflammatory cytokine production compared with nonischemic exercise. NEW & NOTEWORTHY We demonstrate that ischemic, small-muscle endurance exercise elicits local inflammatory cytokine production compared with nonischemic exercise. The present study advances our knowledge of the inflammatory response to exercise in a partial ischemic state, which may be relevant for understanding the therapeutic effects of exercise training for people with ischemic cardiovascular disease-associated comorbidities., (Copyright © 2017 the American Physiological Society.)