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While bones and muscles adapt to mechanical loading, it appears that very specific types of stimuli must be applied to achieve osteogenesis. Our study assessed musculoskeletal outcomes to 30 training sessions on an Inertial Exercise Trainer (Newnan, GA). Subjects (n = 13) performed workouts with their left leg, while their right served as an untreated control. Workouts entailed three 60-s sets each of knee extension, hip extension and calf press exercises, separated by 90-s rests. Before and after the 30 training sessions, subjects underwent strength tests (knee and ankle extensors of both legs), DEXA scans (hip, knee and ankles of both legs), and blood draws. After 30 training sessions 2 x 2 ANOVAs showed left leg peak torques rose significantly. 2 x 2 ANCOVAs, with bone scan area as a covariate, showed significant left leg calcaneal bone mineral content (+ 29 %) and density (+ 33 %) increases after 30 training sessions. A significant decline in C-terminal telopeptides of type I collagen, a blood marker of bone resorption, also occurred after 30 training sessions. The Inertial Exercise Trainer's large volume of training session repetitions elicited high peak force, peak acceleration and impulses that likely provided a mechanical loading stimulus that evoked calcaneal accretion. [ABSTRACT FROM AUTHOR]

In a randomized double-blind study, subjects (n = 34) performed two workouts on a cycle ergometer to estimate their VO2 max. Workouts were preceded by intake of a 2% sucrose solution, one of which was an electrolyte-rich sport beverage (Outlast; Houston, TX) while the other was devoid of added electrolytes and served as a placebo. Heart rates (HR) were recorded before, at four times during, and after workouts. A rating of perceived exertion (RPE) was provided at the end of workouts. There were significant inter-time differences for HR. RPE and VO2 max each had inter-gender differences. Per dependent variable there were no inter-treatment differences. While little research exists on the ergogenic effects of formulations with the electrolyte and carbohydrate concentrations of Outlast, our results concur with prior study outcomes that noted a lack of inter-treatment differences. Our study's environmental conditions and the types of subjects examined may have also contributed to the lack of an ergogenic effect. [ABSTRACT FROM AUTHOR]

Objectives: The synergistic effect of resistance exercise and protein ingestion on muscle protein anabolism in young adults has been well described. However, it is unclear if this relationship is maintained in older adults who are at greater risk of sarcopenic muscle loss. To this end, we sought to determine if the synergistic response to a bout of resistance exercise and a protein-rich lean beef meal was altered by age. Setting: The University of Texas Medical Branch, Clinical Research Center, Galveston, Texas. Participants: Healthy young (n=7, 29±3 y) and older (n=7, 67±2 y) adults. Design: Mixed muscle fractional synthesis rate (FSR) was calculated during a 3 h post-absorptive/rest period and again during a 5 h period following ingestion of a protein-rich meal (340 g lean beef) and bout of resistance exercise (6 sets of 8 repetitions of isotonic knee extension exercise at 80% one repetition maximum). Measurements: Venous blood samples and vastus lateralis muscle biopsy samples were obtained during a primed (2.0 µmol/kg) constant infusion (0.08 µmol·kgmin) of L- [ring-C] phenylalanine. Results: Mixed muscle FSR increased by approximately 108% in both young [pre: 0.073+0.008; post: 0.156±0.021 (SE) %/h, p<0.001] and older adults (pre: 0.075+0.004; post: 0.152+0.017 %/h, p=0.003) following the meal and resistance exercise bout. Conclusion: Aging does not diminish the increase in muscle protein synthesis following a high-quality protein rich meal and bout of resistance exercise. [ABSTRACT FROM AUTHOR]

Background: There is a dearth of literature evaluating the accuracy of Air Displacement Plethysmography (ADP) compared to Dual-energy X-ray Absorptiometry (DXA) for assessing body composition in individuals with lower limb amputations. Validity of ADP in persons with lower limb amputations must be established., Objective: The objective of this study was to compare body composition in persons with lower limb amputations using the BOD POD ® and DXA., Methodology: Body composition was performed on eleven lower limb prosthesis users (age 53.2±14.3 years, weight 81.9±22.3kg) using ADP and DXA with and without prosthesis., Findings: Repeated measures ANOVA indicated no significant difference in body composition among and between trials, F(3,8)= 3.36, p= 0.075. There were no significant differences in Body Fat (BF) percentage with and without prostheses on the BOD POD (28.5±15.7% and 33.7±12.1%, respectively) nor the DXA (32.9±10.6% and 32.0±9.9%, respectively). Association between the BOD POD and DXA were greatest when prostheses were not worn compared to when they were worn. Bland-Altman plots indicate agreement between BOD POD ® and DXA was greatest while wearing the prosthesis., Conclusion: This study is a first to compare total body fat percent between the BOD POD ® and DXA in lower limb prosthesis users. BOD POD ® report valid indices of BF%. Future work will utilize the BOD POD ® in intervention studies for monitoring body composition changes across the continuum of rehabilitation., Competing Interests: The authors declare no financial and personal relationships with organizations or individuals that might have influenced their research., (Copyright (c) 2023 Smith JD, Guerra G, Symons TB, Kwon EH, Yoon EJ.)

Sarcopenia associated with the normal aging process is often combined with the detrimental effects of a sedentary lifestyle in older adults, leading to a significant reduction in reserve capacity of the neuromuscular system. A clear example of the aging effect is the pattern of reduction in muscle strength after the sixth decade for both isometric and concentric contractions. However, older adults are relatively stronger for movements in which muscles lengthen, due to the inherent advantage of eccentric contractions, plus their stiffer muscle structures and prolonged myosin cross-bridge cycles. Also, the capacity for physiological adaptations in the motor pathways remains into very old age when an appropriate exercise stimulus is given, and older adults can obtain adaptations in both enhanced neural control of motor units and increased protein synthesis leading to moderate muscle hypertrophy. Since periods of sedentary lifestyle or bed rest due to illness can have severe detraining consequences on the neuromuscular function of an older person, long-term prevention strategies are advocated to avoid excessive physical impairments and activity restrictions in this age group.