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Background. Age-related decline in muscle power may be an early indicator of balance deficits and fall risk, even in nonfrail adults. This study examined the dose-dependent effect of power training on balance performance in healthy older adults. Methods. One hundred twelve community-dwelling healthy older adults (69 [+ or -] 6 years) were randomized to 8-12 weeks of power training at 20% (LOW), 50% (MED), or 80% (HIGH) of maximal strength, or a nontraining control (CON) group. Participants trained twice weekly (five exercises: three sets of eight rapid concentric/slow eccentric repetitions) using pneumatic resistance machines. Balance, muscle performance (strength, power, endurance, contraction velocity), and body composition were measured. Results. Power training significantly improved balance performance (p .006) in participants who underwent power training compared to controls. Low intensity power training produced the greatest improvement in balance performance (p = .048). Average contraction velocity at low load (40% one repetition maximum [IRM]) fit baseline independently predicted improvement in balance following training (r = -.29, p = .004). Conclusions. Power training improves balance, particularly using a low load, high velocity regimen, in older adults with initial lower muscle power and slower contraction. Further studies are warranted to define the mechanisms underlying this adaptation, as well as the optimum power training intensity for a range of physiological and clinical outcomes in older adults with varying levels of health status and functional independence.

Background. Muscle power (force x velocity) recedes at a faster rate than strength with age and may also be a stronger predictor of fall risk and functional decline. The optimal training paradigm for improving muscle power in older adults is not known, although some literature suggests high velocity, low load training is optimal in young adults. Methods. One hundred twelve healthy older adults (69 [+ or -] 6 years) were randomly assigned to either explosive resistance training at 20% (G20), 50% (G50), or 80% (G80) one repetition maximum (1RM) for 8-12 weeks or to a nontraining control group (CON). Participants trained twice per week (five exercises; three sets of eight rapidly concentric and slow eccentric repetitions) using pneumatic resistance machines. Repeated-measures analysis of variance and covariance (ANOVA and ANCOVA) were used to determine the effects of training. Results. Average peak power increased significantly and similarly in G80 (14 [+ or -] 8%), G50 (15 [+ or -] 9%), and G20 (14 [+ or -] 6%) compared to CON (3 [+ or -] 6%) (p < .0001). By contrast, a positive dose-response relationship with training intensity was observed for relative changes in average strength (r = .40, p = .0009) and endurance (r = .43, p = .0005). Average strength increased in G80 (20 [+ or -] 7%), G50 (16 [+ or -] 7%), and G20 (13 [+ or -] 7%) compared to CON (4 [+ or -] 4%) (p < .0001). Average muscle endurance increased in G80 (185 [+ or -] 126%, p < .0001), G50 (103 [+ or -] 75%, p = .0004), and G20 (82 [+ or -] 57%, p = .0078) compared to CON (28 [+ or -] 29%). Conclusion. Peak muscle power may be improved similarly using light, moderate, or heavy resistances, whereas there is a dose-response relationship between training intensity and muscle strength and endurance changes. Therefore, using heavy loads during explosive resistance training may be the most effective strategy to achieve simultaneous improvements in muscle strength, power, and endurance in older adults.

Objective: To determine the effect of training intensity on the contributions of force and velocity to improvements in peak power (PP) after explosive resistance training in older adults. Methods: 112 healthy older adults (69 ± 6 yr) were randomized to explosive resistance training at 20% (G20), 50% (G50), or 80% (G80) maximal strength (1-repetition maximum) for 8-12 wk (twice weekly, 5 exercises, 3 sets of 8 explosive concentric/slow eccentric repetitions) using pneumatic resistance machines or a nontraining control group (CON). Results: Force at peak power (FPP) increased significantly and similarly among training groups compared with CON. Velocity at peak power (VPP) did not improve significantly and remained similar between all groups. Force contributed significantly more to PP production in G80 and G50 than in CON. The change in PP was independently predicted by changes in fat-free mass in G80 and by changes in both FPP and VPP in G50 and G20. Conclusion: Explosive resistance training in older adults results in the ability to produce higher PP outputs with heavier loads without loss of movement velocity. Moderate- to high-intensity training induced a greater relative contribution of force to PP production in this cohort. [ABSTRACT FROM AUTHOR]

OBJECTIVE--To investigate changes in body composition after 12 months of high-intensity progressive resistance training (PRT) in relation to changes in insulin resistance (IR) or glucose homeostasis in older adults with type 2 diabetes. RESEARCH DESIGN AND METHODS--One-hundred three participants were randomized to receive either PRT or sham exercise 3 days per week for 12 months. Homeostasis model assessment 2 of insulin resistance (HOMA2-IR) and glycosylated hemoglobin (HbA1c) were used as indices of IR and glucose homeostasis. Skeletal muscle mass (SkMM) and total fat mass were assessed using bioelectrical impedance. Visceral adipose tissue, mid-thigh cross-sectional area, and mid-thigh muscle attenuation were quantified using computed tomography. RESULTS--Within the PRT group, changes in HOMA2-IR were associated with changes in SkMM (r = 20.38; P = 0.04) and fat mass (r = 0.42; P = 0.02). Changes in visceral adipose tissue tended to be related to changes in HOMA2-IR (r = 0.35; P = 0.07). Changes in HbA1c were related to changes in mid-thigh muscle attenuation (r = 0.52; P = 0.001). None of these relationships were present in the sham group (P > 0.05). Using ANCOVA models, participants in the PRT group who had increased SkMM had decreased HOMA2-IR (P = 0.05) and HbA1c (P = 0.09) compared with those in the PRT group who lost SkMM. Increases in SkMM in the PRT group decreased HOMA2-IR (P = 0.07) and HbA1c (P < 0.05) compared with those who had increased SkMM in the sham group. CONCLUSIONS--Improvements in metabolic health in older adults with type 2 diabetes were mediated through improvements in body composition only if they were achieved through high-intensity PRT. [ABSTRACT FROM AUTHOR]

Background. Muscle power (force x velocity) recedes at a faster rate than strength with age and may also be a stronger predictor of fall risk and functional decline. The optimal training paradigm for improving muscle power in older adults is not known, although some literature suggests high velocity, low load training is optimal in young adults. Methods. One hundred twelve healthy older adults (69 ± 6 years) were randomly assigned to either explosive resistance training at 20% (G20), 50% (G50), or 80% (G80) one repetition maximum (IRM) for 8-12 weeks or to a nontraining control group (CON). Participants trained twice per week (five exercises; three sets of eight rapidly concentric and slow eccentric repetitions) using pneumatic resistance machines. Repeated-measures analysis of variance and covariance (ANOVA and ANCOVA) were used to determine the effects of training. Results. Average peak power increased significantly and similarly in G80 (14 ± 8%), G50 (15 ± 9%), and G20 (14 ± 6%) compared to CON (3 ± 6%) (p < .0001). By contrast, a positive dose-response relationship with training intensity was observed for relative changes in average strength (r = .40, p = .0009) and endurance (r = .43, p = .0005). Average strength increased in G80 (20 ± 7%). G50 (16 ± 7%), and G20 (13 ± 7%) compared to CON (4 ± 4%) (p < .0001). Average muscle endurance increased in G80 (185 ± 126%, p < .0001), G50 (103 ± 75%. p = .0004), and G20 (82 ± 57%, p = .0078) compared to CON (28 ± 29%). Conclusion. Peak muscle power may be improved similarly using light, moderate, or heavy resistances, whereas there is a dose-response relationship between training intensity and muscle strength and endurance changes. Therefore, using heavy loads during explosive resistance training may be the most effective strategy to achieve simultaneous improvements in muscle strength, power, and endurance in older adults. [ABSTRACT FROM AUTHOR]