The aging process is associated with loss of muscle mass and strength and decline in physical functioning. The term sarcopenia is primarily defined as low level of muscle mass resulting from age-related muscle loss, but its definition is often broadened to include the underlying cellular processes involved in skeletal muscle loss as well as their clinical manifestations. The underlying cellular changes involve weakening of factors promoting muscle anabolism and increased expression of inflammatory factors and other agents which contribute to skeletal muscle catabolism. At the cellular level, these molecular processes are manifested in a loss of muscle fiber cross-sectional area, loss of innervation, and adaptive changes in the proportions of slow and fast motor units in muscle tissue. Ultimately, these alterations translate to bulk changes in muscle mass, strength, and function which lead to reduced physical performance, disability, increased risk of fall-related injury, and, often, frailty. In this review, we summarize current understanding of the mechanisms underlying sarcopenia and age-related changes in muscle tissue morphology and function. We also discuss the resulting long-term outcomes in terms of loss of function, which causes increased risk of musculoskeletal injuries and other morbidities, leading to frailty and loss of independence.

Purpose: Androgen suppression therapy (AST) results in musculoskeletal toxicity that reduces physical function and quality of life. This study examined the impact of a combined resistance and aerobic exercise program as a countermeasure to these AST-related toxicities. Patients and Methods: Between 2007 and 2008, 57 patients with prostate cancer undergoing AST (commenced > 2 months prior) were randomly assigned to a program of resistance and aerobic exercise (n = 29) or usual care (n = 28) for 12 weeks. Primary end points were whole body and regional lean mass. Secondary end points were muscle strength and function, cardiorespiratory capacity, blood biomarkers, and quality of life. Results: Analysis of covariance was used to compare outcomes for groups at 12 weeks adjusted for baseline values and potential confounders. Patients undergoing exercise showed an increase in lean mass compared with usual care (total body, P = .047; upper limb, P < .001; lower limb, P = .019) and similarly better muscle strength (P < .01), 6-meter walk time (P = .024), and 6-meter backward walk time (P = .039). Exercise also improved several aspects of quality of life including general health (P = .022) and reduced fatigue (P = .021) and decreased levels of C-reactive protein (P = .008). There were no adverse events during the testing or exercise intervention program. Conclusion: A relatively brief exposure to exercise significantly improved muscle mass, strength, physical function, and balance in hypogonadal men compared with normal care. The exercise regimen was well tolerated and could be recommended for patients undergoing AST as an effective countermeasure to these common treatment-related adverse effects.

This individual patient data meta-analysis aimed to evaluate the effects of exercise on quality of life (QoL) and physical function (PF) in patients with cancer, and to identify moderator effects of demographic (age, sex, marital status, education), clinical (body mass index, cancer type, presence of metastasis), intervention-related (intervention timing, delivery mode and duration, and type of control group), and exercise-related (exercise frequency, intensity, type, time) characteristics. Relevant published and unpublished studies were identified in September 2012 via PubMed, EMBASE, PsycINFO, and CINAHL, reference checking and personal communications. Principle investigators of all 69 eligible trials were requested to share IPD from their study. IPD from 34 randomised controlled trials (n=4519 patients) that evaluated the effects of exercise compared to a usual care, wait-list or attention control group on QoL and PF in adult patients with cancer were retrieved and pooled. Linear mixed-effect models were used to evaluate the effects of the exercise on post-intervention outcome values (z-score) adjusting for baseline values. Moderator effects were studies by testing interactions. Exercise significantly improved QoL (β=0.15, 95%CI=0.10;0.20) and PF (β=0.18, 95%CI=0.13;0.23). The effects were not moderated by demographic, clinical or exercise characteristics. Effects on QoL (βdifference_in_effect=0.13, 95%CI=0.03;0.22) and PF (βdifference_in_effect=0.10, 95%CI=0.01;0.20) were significantly larger for supervised than unsupervised interventions. In conclusion, exercise, and particularly supervised exercise, effectively improves QoL and PF in patients with cancer with different demographic and clinical characteristics during and following treatment. Although effect sizes are small, there is consistent empirical evidence to support implementation of exercise as part of cancer care.

Background High-intensity interval training (HIIT) may be a feasible and efficacious strategy for improving health-related fitness in young people. The objective of this systematic review and meta-analysis was to evaluate the utility of HIIT to improve health-related fitness in adolescents and to identify potential moderators of training effects. Methods Studies were considered eligible if they: (1) examined adolescents (13–18 years); (2) examined health-related fitness outcomes; (3) involved an intervention of ≥4 weeks in duration; (4) included a control or moderate intensity comparison group; and (5) prescribed high-intensity activity for the HIIT condition. Meta-analyses were conducted to determine the effect of HIIT on health-related fitness components using Comprehensive Meta-analysis software and potential moderators were explored (ie, study duration, risk of bias and type of comparison group). Results The effects of HIIT on cardiorespiratory fitness and body composition were large, and medium, respectively. Study duration was a moderator for the effect of HIIT on body fat percentage. Intervention effects for waist circumference and muscular fitness were not statistically significant. Conclusions HIIT is a feasible and time-efficient approach for improving cardiorespiratory fitness and body composition in adolescent populations.

Objectives: To examine the association between physical activity and inflammatory markers, with consideration for body fatness and antioxidant use. Design: Cross‐sectional study, using baseline data from the Health, Aging and Body Composition Study. Setting: Metropolitan areas surrounding Pittsburgh, Pennsylvania, and Memphis, Tennessee. Participants: Black and white, well‐functioning men and women (N=3,075), aged 70 to 79. Measurements: Interviewer‐administered questionnaires of previous‐week household, walking, exercise, and occupational/volunteer physical activities. Analysis of covariance was used to examine the association between activity level and serum C‐reactive protein (CRP), interleukin‐6 (IL‐6), and plasma tumor necrosis factor alpha (TNFα) with covariate adjustment. Antioxidant supplement use (multivitamin, vitamins E or C, beta carotene) was evaluated as an effect modifier of the association. Results: Higher levels of exercise were associated with lower levels of CRP ( P<. 01), IL‐6 ( P<. 001), and TNFα ( P=. 02) (e.g., CRP=1.95 mg/L for no exercise and 1.72 for >180 min/wk). Adjustment for body fatness attenuated the associations somewhat. Use of antioxidant supplements modified the CRP ( P _interaction =.01) and IL‐6 ( P _interaction =.08) associations such that concentrations were low in those taking supplements (e.g., CRP=1.79–1.84 across exercise levels) and higher in nonsupplement users who did no exercise (2.03) than in those who did the most (1.72). Among nonexercisers, higher levels of other physical activity were related to lower levels of CRP ( P<. 01) and IL‐6 ( P=. 02) but not TNFα ( P=. 36), even after accounting for body fat. Conclusion: Inflammatory markers are lower in older adults with higher levels of exercise and nonexercise activity and in antioxidant supplement users regardless of exercise level.

Background. Chronic inflammation has been proposed as a biological mechanism underlying the decline in physical function that occurs with aging. The purpose of this investigation was to examine the cross-sectional and prospective relationships between markers of inflammation, interleukin-6 (IL-6) and C-reactive protein (CRP), with several measures of physical performance in older persons aged 70 to 79 years. Methods. Subjects were 880 high-functioning men and women participating in the MacArthur Study of Successful Aging (n = 1189), a subset of the Established Populations for Epidemiologic Studies of the Elderly (n = 4030). Plasma IL-6 and CRP levels were determined by enzyme-linked immunosorbent assay and log transformed to normalize the distributions. Physical function measures included handgrip strength, signature time, chair stands (time to complete five repetitions), and 6-m walk time. Results. Women had lower (p < .05) IL-6 levels than men, but there was no significant difference between blacks and whites. IL-6 and CRP levels were higher (p < .05) in current smokers than in nonsmokers and in those with a greater body mass index (BMI). Hours per year undertaking moderate and strenuous physical activity were also related to inflammatory markers with higher (p < .001) IL-6 and CRP levels in less active individuals. After adjusting for age, sex, race, BMI, smoking status, use of nonsteroidal anti-inflammatory drugs, and prevalence of morbidity, those in the top two quartiles for walking speed had lower (p = .012) IL-6 levels than those in the bottom quartile. In addition, there was a trend (p = .038) for lower CRP levels in those with higher walking speed. CRP levels were also lower (p = .04) in individuals in the top quartile for grip strength. No significant differences were noted for chair stands or signature time performance. Repeat performance measures obtained on 405 subjects (67% of those eligible at baseline) obtained 7 years later had declined significantly (grip strength, 18%; signature time, 21%; walking speed, 31%; p < .001), except for the chair rise; however, baseline IL-6 and CRP were not associated with a change in performance. However, those who died or who were unable to undergo testing had higher baseline IL-6 and CRP levels (p < .01) and slower walking speed (p < .05). Conclusions. Although IL-6 has been shown to predict onset of disability in older persons and both IL-6 and CRP are associated with mortality risk, these markers of inflammation have only limited associations with physical performance, except for walking measures and grip strength at baseline, and do not predict change in performance 7 years later in a high-functioning subset of older adults.