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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.

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.

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.

Near-infrared spectroscopy (NIRS) has become an increasingly valuable tool to monitor tissue oxygenation (Toxy) in vivo. Observations of changes in the absorption of light with Toxy have been recognized as early as 1876, leading to a milestone NIRS paper by Jobsis in 1977. Changes in the absorption and scatting of light in the 700–850-nm range has been successfully used to evaluate Toxy. The most practical devices use continuous-wave light providing relative values of Toxy. 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: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.

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 wel...

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., We developed and tested the reliability of a novel bilateral near infrared spectroscopy protocol to estimate mitochondrial capacity (k) in the vastus lateralis and hamstring muscles of active younger men and women. Within‐visit intraclass correlations were moderately high, but between‐visit repeatability of k in these muscles was lower than expected in a subset of women. Bilateral estimates of k are feasible and time efficient even in the hamstring muscles, but further studies employing this protocol will be needed to identify sources of variation between days.

Introduction: Parkinson's disease (PD) is associated with loss of motor control and difficulty exercising. This study measured skeletal muscle mitochondrial capacity and endurance in individuals with and without PD using novel non-invasive methods. We hypothesized that individuals with PD will have decreased mitochondrial capacity, reduced oxygen recovery, and decreased endurance compared to controls. Methods: Eight participants with PD and nine healthy controls were tested. Mitochondrial capacity was measured as the rate of recovery of muscle metabolism after electrical stimulation using near-infrared spectroscopy (NIRS) and repeated short arterial occlusions. Oxygen recovery was measured as the half time of recovery of oxygen levels after 5 minutes of ischemia. Muscle endurance was determined from changes in twitch contraction acceleration during electrical stimulation at 2, 4, and 6 Hz. Results: Mitochondrial capacity was lower in individuals with PD compared to controls (1.5±0.1min-1 vs. 1.7±0.1min-1, p=0.02). Individuals with PD had slower oxygen recovery after ischemia compared to controls (8.9±2.3s vs. 5.4±0.8s, p=0.01). Endurance was not different between groups at 6 Hz (PD vs controls: 58±23% vs. 69±16%, p=0.34). The effect sizes for mitochondrial capacity and oxygen recovery were large (Cohen's d >0.8). The Cohen's d for endurance was 1.11. Conclusion: Individuals with PD had slight impairments in mitochondrial capacity and blood flow but did not have reduced muscle endurance. While our study suggests that muscle metabolic dysfunction may play a minor role in exercise intolerance in people with PD, it demonstrates the use of noninvasive technologies to evaluate muscle function in people with neurological disorders.

Background/Purpose: Multiple sclerosis (MS) is a progressive neurological disease that results in increased fatigue, decreased muscle function, and impaired gait and balance. The purpose of this study was to evaluate the relationship between lower leg muscle function and changes in gait and balance immediately and 20 minutes after 6mins walk-induced fatigue. Methods: Six persons with MS (Patient-Determined Disease Steps 3-5) participated in the study. Perceived fatigue and demographic information were taken at baseline. Muscle fatigability and mitochondria capacity was measured in the lower leg muscles before walking. Reported fatigue (VAFS, 0-10), gait variability, gait asymmetry, and static balance were measured before and immediately after a self-paced 6 minutes treadmill walk with slight elevation, and after 20 minutes of rest. Results: Participant’s baseline MFIS score ranged from 14 - 71. There was a 173% increase in reported fatigue scores after walking. Gait was impaired with a ~26% increase in gait variability and ~40% increase in gait asymmetry immediately after walking (Cohen’s D = 0.4, 0.3 respectively). There was also ~69% increase in balance postural sway with eyes opened and a ~20% increase with eyes closed (Cohen’s D = 0.5, 0.2 respectively). Gait and balance remained impaired after 20 minutes of rest. The decline in gait parameters after walking had a negative correlation with muscle endurance (r=-0.80, p=0.03), and mitochondrial capacity (r=-0.92, p

Our study used near-infrared spectroscopy (NIRS) to measure muscle oxidative capacity (mVmax) in the medial gastrocnemius, vastus lateralis, biceps brachii, and wrist flexor muscles in Cross-country (LEG-T) and Swimmer/Rowers (WHOLE-T) and controls. Young male adults: cross-country LEG-Tners (n=6) and swimmers/rowers (n=5), moderately fit (CONTROL, n=7) were tested. mVmax was measured as the rate of post-exercise recovery of oxygen consumption after a short bout of exercise using NIRS. Whole-body peak oxygen uptake (VO2peak) was determined during a continuous treadmill protocol. The lower limb muscles had 42% higher mVmax than upper limb muscles in all subjects, with significant differences in 10 of 12 pairwise comparisons (p< 0.05). The LEG-T group had higher mVmax values in both legs than CONTROL group (p< 0.05), while the WHOLE-T group had higher mVmax in the vastus lateralis (p = 0.048). There were no differences in the arm muscles of between the groups. The combined mVmax of both leg muscles in all groups correlated with VO2peak (r2=0.597). Muscle oxidative capacity was consistent with training status, and leg mitochondrial capacity correlated with maximal whole body oxidative capacity. These results support the use of NIRS measurements to characterize oxidative capacity in skeletal muscles of athletic populations.

Previous studies have used an accelerometer to evaluate muscle endurance. This study compared endurance index values using a video phone to an accelerometer. Eleven healthy subjects (19-22yrs) were electrically stimulated for 5 minutes at 5 Hz on the hamstring muscles. Four 10s videos were captured at 1080p and 60fps (~283,000 pixels) with the phone. Videos were analyzed using sequential correlations (consecutive 1-2, or consecutive skipping an image 1–3) of the video images between the electrodes. The magnitude of the decrease in the correlation was used to indicate movement. A triaxial accelerometer measured the resultant vector of the movements and the decrease in acceleration was used to indicate fatigue. Analysis using 1-3 produced higher delta R2 values compared to 1-2 (0.038+0.004; 0.020+0.001). Endurance index was 72.1+19.4% for the accelerometer and 71.1+18.6% for the phone images, p=0.64. The mean difference between the methods was not different from zero and the 90% confidence interval was within 5%. In conclusion, the consecutive correlations method detected decreases in movement due to fatigue. The video method provided equivalent values to the previously established accelerometer method to measure muscle endurance. These results support the use of video to assess muscle acceleration during muscle specific endurance test.

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.

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 (R2 = 0.68–0.71, P < .01) and muscle endurance (R2 = 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 (R2 = 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.

Diaphragmatic function is important in treating respiratory failure. Muscle endurance has been measured using twitch electrical stimulation and accelerometer-based mechanomyography. The purpose of this study was to evaluate the reproducibility and the time to perform an endurance test on the diaphragm muscle using electrical stimulation of the phrenic nerve. Twenty healthy subjects (21.6±1.6yrs) were tested in the supine position on two separate occasions. Stimulation electrodes were placed on the left (n=18) or right (n=2) phrenic nerve underneath the sternocleidomastoid muscle. A tri-axial accelerometer was placed on the abdomen and 5 minutes of submaximal electrical stimulation at 5Hz was performed. The resultant vector of acceleration at peak and end acceleration was analyzed: endurance index = end/peak*100). The test was successfully completed 41/47 times. The endurance index for the two days was 73.8±9.4% and 72.6±11.1%, respectively. The time to find the phrenic nerve was 34.8±13.1s for the first 10 subjects and 13.0±2.8s for the second 10 subjects. For the second group, the mean difference in endurance between days was 0.03% with a 95% confidence interval of -1.6% to 1.5%. In conclusion, the diaphragm endurance test was reproducible with practice.

Muscle endurance has been measured using an electrical stimulation twitch protocol and an accelerometer. This protocol used stimulation frequencies of 2, 4, and 6 Hz over nine minutes. This study compared endurance index values using a shorter protocol of 5 Hz for 5 Minutes to the original nine minute protocol. Fifteen healthy subjects (19-22yrs) were electrically stimulated on the forearm muscles twice: one day for 5 minutes at 5 Hz and on another day for 3 minutes at each at 2, 4 and 6 Hz. A triaxial accelerometer measured the resultant vector of the movements and the decrease in acceleration was used to indicate fatigue. There was no difference in Endurance Index (EI) between the 5 and 9 minute protocols (63.2+18.7%, 64.1+19.8%, respectively, p=0.532). The correlation between the two EI measurements was y= 0.91x+4.99%, r2=0.93. Equivalency testing found the mean difference between EI values for the two methods was 0.88% with a 95% confidence interval of the difference in EI of -2.09 to 3.81%. In conclusion, the shorter 5 Hz five minute endurance index protocol provided similar results to the longer 2 ,4, 6 Hz nine minute protocol. These results support the use of the shorter protocol when measuring muscle specific endurance.

RationaleSupervised 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.ObjectiveWe 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 resultsPatients 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 ConclusionsOxygen-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.

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.

Metformin is used clinically to reduce fasting glucose with minimal effects on postprandial glucose. Postmeal exercise reduces postprandial glucose and may offer additional glucose-lowering benefit beyond that of metformin alone, yet controversy exists surrounding exercise and metformin interactions. It is currently unknown how postmeal exercise and metformin monotherapy in combination will affect postprandial glucose. Thus, we examined the independent and combined effects of postmeal exercise and metformin monotherapy on postprandial glucose. A randomized crossover design was used to assess the influence of postmeal exercise on postprandial glucose excursions in 10 people treated with metformin monotherapy (57 ± 10 yr, HbA1C = 6.3 ± 0.6%). Each participant completed the following four conditions: sedentary and postmeal exercise (5 × 10-min bouts of treadmill walking at 60% V̇o2max) with metformin and sedentary and postmeal exercise without metformin. Peak postprandial glucose within a 2-h time window and 2-h total area under the curve was assessed after a standardized breakfast meal, using continuous glucose monitoring. Postmeal exercise significantly blunted 2-h peak ( P = 0.001) and 2-h area under the curve ( P = 0.006), with the lowest peak postprandial glucose excursion observed with postmeal exercise and metformin combined ( P < 0.05 vs. all other conditions: metformin/sedentary: 12 ± 3.4, metformin/exercise: 9.7 ± 2.3, washout/sedentary: 13.3 ± 3.2, washout/exercise: 11.1 ± 3.4 mmol/l). Postmeal exercise and metformin in combination resulted in the lowest peak postprandial glucose excursion compared with either treatment modality alone. Exercise timed to the postprandial phase may be important for optimizing glucose control during metformin monotherapy. NEW & NOTEWORTHY The interactive effects of metformin and exercise on key physiological outcomes remain an area of controversy. Findings from this study show that the combination of metformin monotherapy and moderate-intensity postmeal exercise led to beneficial reductions in postprandial glucose excursions. Postmeal exercise may be a useful strategy for the management of postprandial glucose in people on metformin.

Aims Type 2 diabetes treatment primarily focuses on reducing hyperglycemia, including postprandial glucose excursions. Hypoglycemic agents are used clinically to lower fasting and postprandial glucose. Metformin is the first-line therapy; however, if metformin is inadequate then ‘add-on’ hypoglycemic agents are implemented. Postmeal exercise has been shown to lower postprandial glucose. The aim of this study was to assess if postmeal exercise provides additional glucose-lowering benefit, beyond medication alone, in those on add-on hypoglycemic agents. Methods Postprandial glucose excursions in eight participants with type 2 diabetes (Age: 60 ± 10.7, HbA1C: 7.9 ± 2.3) being treated with add-on hypoglycemic agents were assessed during both drug-treated sedentary and drug-treated postmeal exercise conditions. Continuous glucose monitoring was used to assess peak and area under the glucose curve (AUC) during exercise, as well as peak within a 2-h time window, 2-h total and 2-h incremental AUC after a standardized breakfast meal. Postmeal exercise consisted of 3 × 10-min intervals of treadmill walking at 50% maximal oxygen uptake. Results Glucose peak (drug only: 13.8 ± 3.7, drug/exercise: 9.9 ± 2.7 mmol/L; p = 0.02) and AUC (drug only: 500 ± 136, drug/exercise: 357 ± 89 mmol/L × 40 min; p = 0.03) were reduced during postmeal exercise. Breakfast 2-h incremental AUC was also reduced (drug only: 585 ± 291, drug/exercise: 330 ± 294; p = 0.047). Discussion Post-breakfast exercise lowered glucose during the exercise bout, although this effect was not sustained on later meals.

Introduction: Spinal cord injury (SCI) results in skeletal muscle atrophy, increases in intramuscular fat, and reductions in skeletal muscle oxidative capacity. Endurance training elicited with neuromuscular electrical stimulation (NMES) may reverse these changes and lead to improvement in muscle metabolic health. Methods: Fourteen participants with complete SCI performed 16 weeks of home-based endurance NMES training of knee extensor muscles. Skeletal muscle oxidative capacity, muscle composition, and blood metabolic and lipid profiles were assessed pre- and post-training. Results: There was an increase in number of contractions performed throughout the duration of training. The average improvement in skeletal muscle oxidative capacity was 119%, ranging from –14% to 387% (P = 0.019). There were no changes in muscle composition or blood metabolic and lipid profiles. Conclusion: Endurance training improved skeletal muscle oxidative capacity, but endurance NMES of knee extensor muscles did not change blood metabolic and lipid profiles. Muscle Nerve 55: 669–675, 2017

Background 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 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.

Background Supervised exercise training is recommended for intermittent claudication in peripheral artery disease (PAD), but the relationship between work achieved during exercise and clinical outcomes is not well described. As in other training modalities, increased effort measured by cumulative work production is expected to be translate into to positive performance adaptations. In settings of constrained limb blood flow, this relationship is unknown. In addition, the impact of exercise on skeletal muscle oxygen use capacity changes is unknown. Near infrared spectroscopy (NIRS) offers a method of characterizing skeletal muscle mitochondrial adaptations before and after training programs. Methods We enrolled subjects (n=17, age 71±8.8 years, 20% female) with PAD and intermittent claudication (ankle brachial index [ABI]=0.76±0.21) in a 12-week supervised training program, randomized to traditional pain-based training strategy versus hypoxia-based training (using NIRS to direct training). Muscle work was calculated based on training performance. NIRS-based determination of mitochondrial capacity and microvascular flow were measured at baseline and after 12 weeks. Results Subjects trained for an average of 32.9±5.9 sessions walking at 54.4±13.4 m/min per session. Subjects achieved a mean of average workload of 4767±5112 kilogram force meter (kpm) per session and an aggregate of 148536±148020 kpm for the training program. Baseline pain-free walking time of 2.95±2.10 minutes increased by a mean of 3.74±2.47 minutes. Increase in walking time was proportional to the average work level achieved per session, with a correlating trend to the overall work level performed over 12 weeks (r=0.543, p=0.024). There was no increase in blood flow measured by ABI or limb microcirculation perfusion index over the training period. Skeletal muscle mitochondrial capacity increased over the training period and correlated with the overall work performed (r=0.573, p=0.016). Figure 1 Conclusions Treadmill exercise rehabilitation for intermittent claudication may be guided by total dose of exercise and NIRS-based indices of mitochondrial capacity rather than pain-levels achieved or changes in perfusion measures. Acknowledgement/Funding American Heart Association

Near-Infrared Spectroscopy (NIRS) has been used to measure muscle mitochondrial capacity. The current method requires as many as 22 short ischemic occlusions to generate a recovery curve for mitochondrial capacity. PURPOSE: To determine the effectiveness of using a 6-occlusion analysis protocol to study muscle mitochondrial capacity. METHOD: Two independent, unidentified data sets were analyzed (bicep n=48, forearm n=41) from previous studies using a NIRS device (Artinis, Ltd.). Both data sets had two recovery tests that included 22 ischemic occlusions. A recovery rate used to indicate mitochondrial capacity was calculated two different ways (simultaneously). Each sample was analyzed with a MATLAB program; with a curve-fit for the 22 ischemic occlusions and curve matching for the first six ischemic cuffs and an end resting value. The two resulting rate constants were compared using correlations, both for the two data sets, good and bad fitting data, using the best 5 of 6 points for the 6 cuff approach. RESULTS: The rate constants were not significantly different between the 22 cmuff and 6 cuff for the total data sets: bicep (1.43+0.32min-1, 1.44+0.35min-1, p=0.56), forearm (1.94+0.42min-1, 1.95+0.44min-1, p=0.76). The average bicep rate constants, when compared to each other, had an equation of y=1.07x-0.09, R2=0.90. The average forearm rate constants, when compared to each other, had an equation of 0.98x+0.02, R2=0.93. CONCLUSIONS: The 6-Cuff analysis provided the same results as the longer 22-cuff. The 6-cuff approach is both shorter in time and uses less ischemic occlusion periods, increasing the practicality of the NIRS mitochondrial capacity test.

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.

Key points Reducing excessive oxidative stress, through chronic exercise or antioxidants, can decrease the negative effects induced by excessive amounts of oxidative stress. Transient increases in oxidative stress produced during acute exercise facilitate beneficial vascular training adaptations, but the effects of non-specific antioxidants on exercise training-induced vascular adaptations remain elusive. Circulating angiogenic cells (CACs) are an exercise-inducible subset of white blood cells that maintain vascular integrity. We investigated whether mitochondria-specific antioxidant (MitoQ) supplementation would affect the response to 3 weeks of endurance exercise training in CACs, muscle mitochondrial capacity and maximal oxygen uptake in young healthy men. We show that endurance exercise training increases multiple CAC types, an adaptation that is not altered by MitoQ supplementation. Additionally, MitoQ does not affect skeletal muscle or whole-body aerobic adaptations to exercise training. These results indicate that MitoQ supplementation neither enhances nor attenuates endurance training adaptations in young healthy men. Abstract Antioxidants have been shown to improve endothelial function and cardiovascular outcomes. However, the effects of antioxidants on exercise training-induced vascular adaptations remain elusive. General acting antioxidants combined with exercise have not impacted circulating angiogenic cells (CACs). We investigated whether mitochondria-specific antioxidant (MitoQ) supplementation would affect the response to 3 weeks of endurance exercise training on CD3+ , CD3+ /CD31+ , CD14+ /CD31+ , CD31+ , CD34+ /VEGFR2+ and CD62E+ peripheral blood mononuclear cells (PBMCs), muscle mitochondrial capacity, and maximal oxygen uptake (VO2 max ) in healthy men aged 22.1 ± 0.7 years, with a body mass index of 26.9 ± 0.9 kg m-2 , and 24.8 ± 1.3% body fat. Analysis of main effects revealed that training induced 33, 105 and 285% increases in CD14+ /CD31+ , CD62E+ and CD34+ /VEGFR2+ CACs, respectively, and reduced CD3+ /CD31- PBMCs by 14%. There was no effect of MitoQ on CAC levels. Also independent of MitoQ supplementation, exercise training significantly increased quadriceps muscle mitochondrial capacity by 24% and VO2 max by roughly 7%. In conclusion, endurance exercise training induced increases in multiple CAC types, and this adaptation is not modified by MitoQ supplementation. Furthermore, we demonstrate that a mitochondrial-targeted antioxidant does not influence skeletal muscle or whole-body aerobic adaptations to exercise training.

INTRODUCTION We examined ultrasound-estimated intramuscular fat of 4 muscles: rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA), and medial gastrocnemius (MG), and compared the results with other health measures. METHODS Forty-two participants were tested. Muscle echo intensity was quantified into percent intramuscular fat using previously published equations. RESULTS Strong correlations were found in percent intramuscular fat in the 4 muscles (r ≥ 0.8). Weak to moderate correlations were found between intramuscular fat and body mass index (r ≥ 0.2), waist/hip ratio (r ≥ 0.2), muscle thickness (r = -0.5 in RF, r = -0.4 in TA, r = -0.7 in MG), and muscle strength (leg extension: r = 0.4; leg flexion: r = -0.5). A relationship between intramuscular fat in RF and MG and physical activity was also observed (P

Neuromuscular electrical stimulation (NMES), often referred to as functional electrical stimulation (FES), has been used to activate paralyzed skeletal muscle in people with spinal cord injury (SCI). The goal of NMES has been to reverse some of the dramatic losses in skeletal muscle mass, to stimulate functional improvements in people with incomplete paralysis, and to produce some of the health benefits associated with exercise.The purpose of this brief review is to describe a quantifiable resistance training form of NMES developed by Gary A. Dudley.People with motor complete SCI were first tested to confirm that an NMES-induced muscle contraction of the quadriceps muscle could be achieved. The contraction stimulus consisted of biphasic pulses at 35 Hz performed with increasing current up to what was needed to produce full knee extension. Four sets of 10 knee extensions were elicited, if possible. Training occurred biweekly for 3 to 6 months, with ankle weights being increased up to an added weight of 9.1 kg if the 40 repetitions could be performed successfully for 2 sessions.Many participants have performed this protocol without adverse events, and all participants showed progression in the number of repetitions and/or the amount of weight lifted. Large increases in muscle mass occur, averaging 30% to 40%. Additional physiological adaptations to stimulated muscle have also been reported.These results demonstrate that the affected skeletal muscle after SCI responds robustly to progressive resistance training many years after injury. Future work with NMES should determine whether gains in lean mass translate to improved health, function, and quality of life.

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 (mVO2). Approach: mVO2 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). mVO2 was measured using NIRS during four repeated arterial occlusions at rest, and 5 minutes after exercise consisting of 90 seconds of rapid concentric contractions (5minEPOC). Main results: Resting mVO2 with four measurements was 17.88 ± 3.04%/min on day one and 19.42 ± 3.03%/min on day two (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 and 52.22 ± 22.10%/min, 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 mVO2 similar to that of a four arterial occlusions protocol. While a four arterial occlusion protocol provides similar reliability for post-exercise mVO2 with one arterial occlusion, it reduces the day-to-day variance for resting mVO2 and therefore should be employed for longitudinal studies.

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 (MVO2) 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 0.05 for all comparisons). Conclusions Studies of muscle endurance need to control for muscle length as changes in muscle length can influence muscle endurance.

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).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).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 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.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.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.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.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.

Introduction: The aim of this study was to compare ultrasound echo intensity (EI) with high-resolution T1-weighted MRI and to establish calibration equations to estimate percent intramuscular fat from EI. Methods: Thirty-one participants underwent both ultrasound and MRI testing of 4 muscles: rectus femoris (RF); biceps femoris (BF); tibialis anterior (TA); and medial gastrocnemius (MG). Results: Strong correlations were found between MRI percent fat and muscle EI after correcting for subcutaneous fat thickness (r = 0.91 in RF, r = 0.80 in BF, r = 0.80 in TA, r = 0.76 in MG). Three types of calibration equations were established. Conclusions: Muscle ultrasound is a practical and reproducible method that can be used as an imaging technique for examination of percent intramuscular fat. Future ultrasound studies are needed to establish equations for other muscle groups to enhance its use in both research and clinical settings. Muscle Nerve, 2015

Background Individuals with disabilities are at higher risk of health conditions; thus, there is a need to provide hands-on opportunities for pre-healthcare professionals to interact with individual with disabilities as well as deliver wellness services to this population. Objective Examine the feasibility and effectiveness of a student-led wellness program for individuals with disabilities. Methods Thirty-two undergraduate student wellness coaches between the ages of 19–23 years, and fifteen participants with disabilities, ranging in ages from 28 to 74 years were included in this study. Every participant was assigned to at least 1 student wellness coach with the purpose of establishing an individualized wellness plan. Results After 3 months (fall 2013 academic semester), all wellness coaches demonstrated improved clinical interaction and confidence toward working with the participants. The participants had an average weight loss of 2.0 ± 2.9 kg, ranging from 0.0 to 9.0 kg. All participants had improved functionality and fitness and reported high satisfaction toward the program. Conclusions This study demonstrated the impact of a unique program on the education of pre-healthcare professionals and the overall wellness of participants with disabilities. The program model has the potential to provide clinical health education among pre-healthcare professionals through interacting with individuals with disabilities.

Introduction Exercise intolerance predicts mortality in patients with cystic fibrosis (CF); however, the mechanisms have yet to be fully elucidated. Using near infrared spectroscopy (NIRS), this study compared skeletal muscle oxidative capacity in patients with CF to healthy controls.

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.

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.