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Purpose: It is still equivocal whether oxygen uptake recovery kinetics are limited by oxygen delivery and can be improved by supplementary oxygen. The present study aimed to investigate whether measurements of muscle and pulmonary oxygen uptake kinetics can be used to assess oxygen delivery limitations in healthy subjects. Methods: Sixteen healthy young adults performed three sub-maximal exercise tests (6 min at 40% Wmax) under hypoxic (14%O2), normoxic (21%O2) and hyperoxic (35%O2) conditions on separate days in randomized order. Both Pulmonary VO2 and near infra red spectroscopy (NIRS) based Tissue Saturation Index (TSI) offset kinetics were calculated using mono-exponential curve fitting models. Results: Time constant τ of VO2 offset kinetics under hypoxic (44.9 ± 7.3s) conditions were significantly larger than t of the offset kinetics under normoxia (37.9 ± 8.2s, p = 0.02) and hyperoxia (37±6s, p = 0.04). TSI mean response time (MRT) of the offset kinetics under hypoxic conditions (25.5 ± 13s) was significantly slower than under normoxic (15 ± 7.7, p = 0.007) and hyperoxic (13 ± 7.3, p = 0.008) conditions. Conclusion: The present study shows that there was no improvement in the oxygen uptake and muscle oxygenation recovery kinetics in healthy subjects under hyperoxic conditions. Slower TSI and VO2 recovery kinetics under hypoxic conditions indicate that both NIRS and spiroergometry are appropriate non-invasive measurement tools to assess the physiological response of a healthy individual to hypoxic exercise. [ABSTRACT FROM AUTHOR]

Although spiro-ergometry is the established "gold standard" for determination of the second ventilatory threshold (VT2), it is a costly and rather time-consuming method. Previous studies suggest that assessing the second anaerobic threshold (AT2) on the basis of heart rate variability (HRV) during exercise may be a more cost-effective and noninvasive manner. However, appropriate validation studies, are still lacking. Eleven healthy, moderately trained subjects underwent 3 incremental exercise tests. Ventilation, oxygen uptake (V[Combining Dot Above]O2), CO2 production (...CO2), and HRV were measured continuously. Exercise testing was performed in 3 oxygen (FiO2) conditions of inspired air (14, 21, and 35% of oxygen). Participants and assessors were blinded to the FiO2 conditions. Two research teams assessed VT2s and HRVT2s independently from each other. Mean workloads corresponding to VT2 and HRVT2 in hypoxia were, respectively, 19 ± 17% (p = 0.01) and 15 ± 15% (p = 0.1) lower in comparison with hyperoxic conditions. Bland-Altman analysis showed low estimation bias (2.2%) and acceptably precise 95% limits of agreement for workload -15.7% to 20.1% for all FiO2 conditions. Bias was the lowest under normoxic conditions (1.1%) in comparison with hypoxia (3.7%) and hyperoxia (4.7%). Heart rate variability--based AT2 assessment had a most acceptable agreement with VT2 under normoxic conditions. This simple HRVT2 assessment may have potential applications for exercise monitoring in commercial fitness settings. [ABSTRACT FROM AUTHOR]

This study assesses femoral neck shortening and its effect on gait pattern and muscle strength in patients with femoral neck fractures treated with internal fixation. Seventy-six patients from a multicenter randomized controlled trial participated. Patient characteristics and Short Form 12 and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were collected. Femoral neck shortening, gait parameters, and maximum isometric forces of the hip muscles were measured and differences between the fractured and contralateral leg were calculated. Variables of patients with little or no shortening, moderate shortening, and severe shortening were compared using univariate and multivariate analyses. Median femoral neck shortening was 1.1 cm. Subtle changes in gait pattern, reduced gait velocity, and reduced abductor muscle strength were observed. Age, weight, and Pauwels classification were risk factors for femoral neck shortening. Femoral neck shortening decreased gait velocity and seemed to impair gait symmetry and physical functioning. In conclusion, internal fixation of femoral neck fractures results in permanent physical limitations. The relatively young and healthy patients in our study seem capable of compensating. Attention should be paid to femoral neck shortening and proper correction with a heel lift, as inadequate correction may cause physical complaints and influence outcome. [ABSTRACT FROM AUTHOR]

OBJECTIVE — The aim of this study was to investigate the effect of shoe design on the plantar pressure dynamics of patients with diabetic neuropathy during walking. RESEARCH DESIGN AND METHODS Three shoe design categories were tested. Total contact area and biomechanical variables in multiple areas under the foot were measured RESULTS Shoes with a rocker bottom principle reduced pressure 35-65% underneath the heel and the central metatarsal heads. Increased contact area did not result in significant pressure reductions underneath the forefoot. Pressure dynamics underneath the heel and median forefoot (first metatarsal head and hallux) on average showed no significant differences among the different shoes with a cushioning insole. CONCLUSIONS — The most effective way to offload the forefoot of patients with neuropathic feet is through the use of the rocker sole principle. In general, the effect of an insole depends on the design characteristics of a shoe. Predicting the effect of therapeutic footwear on an individual scale, however, remains difficult. Therefore, in-shoe pressure measurements seem to be necessary to evaluate a therapeutic shoe prescription in certain individual cases. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to investigate the effect of shoe design on the plantar pressure dynamics of patients with diabetic neuropathy during walking.Research Design and Methods: Three shoe design categories were tested. Total contact area and biomechanical variables in multiple areas under the foot were measured.Results: Shoes with a rocker bottom principle reduced pressure 35-65% underneath the heel and the central metatarsal heads. Increased contact area did not result in significant pressure reductions underneath the forefoot. Pressure dynamics underneath the heel and medial forefoot (first metatarsal head and hallux) on average showed no significant differences among the different shoes with a cushioning insole.Conclusions: The most effective way to offload the forefoot of patients with neuropathic feet is through the use of the rocker sole principle. In general, the effect of an insole depends on the design characteristics of a shoe. Predicting the effect of therapeutic footwear on an individual scale, however, remains difficult. Therefore, in-shoe pressure measurements seem to be necessary to evaluate a therapeutic shoe prescription in certain individual cases. [ABSTRACT FROM AUTHOR]

The article presents an overview of a study on the impact of protein hydrolysate/leucine coingestion on long-standing type 2 diabetic patients. Co-ingestion of a protein hydrolysate/leucine mixture following each main meal substantially reduces the prevalence of hyperglycemia in these patients. This is accompanied by a significant reduction in average 24-hour blood glucose concentration.

Increased reactive oxygen species (ROS) generation and microvascular endothelial disruptions occur with natural ageing, but often transpire before the detection of cardiometabolic conditions including hypertension. Age-related increases in blood pressure are driven by complex systemic changes with poorly understood integrated mechanisms. The deconditioning experienced by ageing skeletal muscle from mid-life is associated with reduced microvascular blood flow and increased peripheral resistance, suggesting that vasodilatory decrements in the muscle may precede the age-related increases in blood pressure. Structural and functional changes within the vascular and skeletal muscle systems with advancing age can influence redox homeostasis, and vice versa, further compounding microvascular endothelial dysfunction. Therefore, comparisons between the microvascular environments of healthy and hypertensive cohorts can provide insights into the changes that occur during significant periods of functional decline. This comprehensive study protocol describes a microdialysis technique to assess the interactions of microvascular health and functional changes in the muscle, which currently cannot be otherwise addressed. Here, we detail an experimental protocol to simultaneously detect skeletal muscle ROS (H 2 O 2 and indirect O 2 - ), determine nutritive blood flow and assess microvascular endothelial function in response to acetylcholine stimulation. We expect that healthy middle-aged individuals should not have increased ROS generation in the muscle at rest, compared to their hypertensive or older counterparts, but may exhibit perturbed microvascular function. The described technique allows for intricate exploration of microvascular physiology that will provide a critically novel insight into benchmarking potential age-related mechanisms involved in the development of age-related hypertension, and aid in early identification and prevention. KEY POINTS: Increased reactive oxygen species (ROS) production and microvascular endothelial dysfunction precede the onset of age-related cardiometabolic and vascular conditions such as hypertension. The profound structural and functional changes that occur within the vasculature and in skeletal muscle from middle age prompt a need to mechanistically explore the microvascular environment in healthy and hypertensive individuals. Using a novel microdialysis technique, we detail an experimental protocol to simultaneously detect skeletal muscle ROS (H 2 O 2 and indirect O 2 - ), determine nutritive blood flow and assess microvascular endothelial function in response to acetylcholine stimulation. With this technique and study protocol, we can reveal functional insights into potential perturbations in ROS generation at rest and the microvascular endothelium, which play important roles in the development of age-related hypertension., (© 2024 The Authors. The Journal of Physiology © 2024 The Physiological Society.)

The current pilot study investigates whether oral supplementation of specific collagen peptides improves symptoms and tendon vascularisation in patients with chronic mid-portion Achilles tendinopathy in combination with structured exercise. Participants were given a placebo or specific collagen peptides (TENDOFORTE ® ) in combination with a bi-daily calf-strengthening program for 6 months. Group AB received specific collagen peptides for the first 3 months before crossing over to placebo. Group BA received placebo first before crossing over to specific collagen peptides. At baseline (T1), 3 (T2) and 6 (T3) months, Victorian Institute of Sports Assessment⁻Achilles (VISA-A) questionnaires and microvascularity measurements through contrast-enhanced ultrasound were obtained in 20 patients. Linear mixed modeling statistics showed that after 3 months, VISA-A increased significantly for group AB with 12.6 (9.7; 15.5), while in group BA VISA-A increased only by 5.3 (2.3; 8.3) points. After crossing over group AB and BA showed subsequently a significant increase in VISA-A of, respectively, 5.9 (2.8; 9.0) and 17.7 (14.6; 20.7). No adverse advents were reported. Microvascularity decreased in both groups to a similar extent and was moderately associated with VISA-A ( R c ²:0.68). We conclude that oral supplementation of specific collagen peptides may accelerate the clinical benefits of a well-structured calf-strengthening and return-to-running program in Achilles tendinopathy patients.

Mankowski, RT, Michael, S, Rozenberg, R, Stokla, S, Stam, HJ, and Praet, SFE. Heart-rate variability threshold as an alternative for spiro-ergometry testing: a validation study. J Strength Cond Res 31(2): 474-479, 2017-Although spiro-ergometry is the established "gold standard" for determination of the second ventilatory threshold (VT2), it is a costly and rather time-consuming method. Previous studies suggest that assessing the second anaerobic threshold (AT2) on the basis of heart rate variability (HRV) during exercise may be a more cost-effective and noninvasive manner. However, appropriate validation studies, are still lacking. Eleven healthy, moderately trained subjects underwent 3 incremental exercise tests. Ventilation, oxygen uptake (V[Combining Dot Above]O2), CO2 production (V[Combining Dot Above]CO2), and HRV were measured continuously. Exercise testing was performed in 3 oxygen (FiO2) conditions of inspired air (14, 21, and 35% of oxygen). Participants and assessors were blinded to the FiO2 conditions. Two research teams assessed VT2s and HRVT2s independently from each other. Mean workloads corresponding to VT2 and HRVT2 in hypoxia were, respectively, 19 ± 17% (p = 0.01) and 15 ± 15% (p = 0.1) lower in comparison with hyperoxic conditions. Bland-Altman analysis showed low estimation bias (2.2%) and acceptably precise 95% limits of agreement for workload -15.7% to 20.1% for all FiO2 conditions. Bias was the lowest under normoxic conditions (1.1%) in comparison with hypoxia (3.7%) and hyperoxia (4.7%). Heart rate variability-based AT2 assessment had a most acceptable agreement with VT2 under normoxic conditions. This simple HRVT2 assessment may have potential applications for exercise monitoring in commercial fitness settings.

Objective: To assess if a 12-week exercise intervention to improve aerobic fitness, muscle strength, and core stability also had an impact on fatigue, pain, activity, and participation in adults with Pompe disease, an inherited neuromuscular disorder., Design: Open-label trial. Change was assessed by the chi-square test and Wilcoxon signed-rank test., Setting: Physiotherapy practices., Participants: Mildly affected adult patients with Pompe disease who were not dependent on ventilators and/or walking devices and were receiving enzyme replacement therapy., Intervention: Patients participated in a 12-week exercise program, which included 36 sessions of standardized aerobic, resistance, and core stability exercises., Main Outcome Measures: Before and after the training program we evaluated fatigue (Fatigue Severity Scale), pain (yes/no), motor function (Quantitative Muscle Function Test, Rasch-built Pompe-specific Activity Scale), amount of physical activity (activity monitor), and health status (Medical Outcomes Study 36-Item Short-Form Health Survey)., Results: Of the 25 patients enrolled, 23 completed the program. At the end of the program, levels of fatigue (median, 5.33 to 4.78, P=.01) and pain (56.5% to 21.7%, P=.04) improved. The quality of motor function and the amount of physical activity patients engaged in did not change. Changes in pain and fatigue were not related to improvements in aerobic fitness or muscle strength., Conclusions: This study in mildly affected adult patients with Pompe disease suggests that a combined training program aiming to increase aerobic fitness, muscle strength, and core stability also leads to improvements in fatigue and pain., (Copyright © 2015 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.)

Lack of physical activity has been related to an increased risk of developing insulin resistance. This study aimed to assess the impact of chronic muscle deconditioning on whole body insulin sensitivity, muscle oxidative capacity, and intramyocellular lipid (IMCL) content in subjects with paraplegia. Nine subjects with paraplegia and nine able-bodied, lean controls were recruited. An oral glucose tolerance test was performed to assess whole body insulin sensitivity. IMCL content was determined both in vivo and in vitro using (1)H-magnetic resonance spectroscopy and fluorescence microscopy, respectively. Muscle biopsy samples were stained for succinate dehydrogenase (SDH) activity to measure muscle fiber oxidative capacity. Subcellular distributions of IMCL and SDH activity were determined by defining subsarcolemmal and intermyofibrillar areas on histological samples. SDH activity was 57 ± 14% lower in muscle fibers derived from subjects with paraplegia when compared with controls (P < 0.05), but IMCL content and whole body insulin sensitivity did not differ between groups. In muscle fibers taken from controls, both SDH activity and IMCL content were higher in the subsarcolemmal region than in the intermyofibrillar area. This typical subcellular SDH and IMCL distribution pattern was lost in muscle fibers collected from subjects with paraplegia and had changed toward a more uniform distribution. In conclusion, the lower metabolic demand in deconditioned muscle of subjects with paraplegia results in a significant decline in muscle fiber oxidative capacity and is accompanied by changes in the subcellular distribution patterns of SDH activity and IMCL. However, loss of muscle activity due to paraplegia is not associated with substantial lipid accumulation in skeletal muscle tissue.

Aim: Although postprandial hyperglycemia is recognized as an important target in type 2 diabetes treatment, information on the prevalence of postprandial hyperglycemia throughout the day is limited. Therefore, we assessed the prevalence of hyperglycemia throughout the day in type 2 diabetes patients and healthy controls under standardized dietary, but otherwise free-living conditions., Methods: 60 male type 2 diabetes patients (HbA(1c) 7.5±0.1% [58±1 mmol/mol]) and 24 age- and BMI-matched normal glucose tolerant controls were recruited to participate in a comparative study of daily glycemic control. During a 3-day experimental period, blood glucose concentrations throughout the day were assessed by continuous glucose monitoring., Results: Type 2 diabetes patients experienced hyperglycemia (glucose concentrations >10 mmol/L) 38±4% of the day. Even diabetes patients with an HbA(1c) level below 7.0% (53 mmol/mol) experienced hyperglycemia for as much as 24±5% throughout the day. Hyperglycemia was negligible in the control group (3±1%)., Conclusion: Hyperglycemia is highly prevalent throughout the day in type 2 diabetes patients, even in those patients with a HbA(1c) level well below 7.0% (53 mmol/mol). Standard medical care with prescription of oral blood glucose lowering medication does not provide ample protection against postprandial hyperglycemia., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)