The purpose of the study was to determine whether muscle force, power, and optimal length were affected by 4 weeks of static or ballistic stretching. Twenty-nine males (age, 18-60 years) performed 4 maximal hip extensions to measure peak torque (PT), rate of torque development (RTD), work (W), and PT angle (PTA). Then, participants completed 4 weeks of static or ballistic flexibility training of the hip extensors followed by repetition of the testing protocol. After training, PT increased 5.3 +/- 19.0% in the static group (SG), 7.8 +/- 12.7% in the ballistic group (BG), and 6.1 +/- 17.9% in the control group (CG). RTD increased 4.8 +/- 22.7% in the SG, 3.6 +/- 28.0% in the BG and 9.7 +/- 24.0% in the CG. W increased 3.9 +/- 7.0% in the SG, 14.7 +/- 27.4% in the BG, and 5.5 +/- 9.5% in the CG. PTA changed little with a -1.6 +/- 6.6% decrease in the SG and increases of 0.86 +/- 4.1% in the BG and 0.18 +/- 8.7% in the CG. None of the results were statistically different between stretching group and CG (alpha = 0.05). These data suggest that 4 weeks of stretching have little effect on muscle strength, power, W, or length-tension relationship. PTA changed little, suggesting that a lengthening of the muscle with stretching did not occur. It is suggested that individuals can routinely stretch following exercise to maintain flexibility but should avoid stretching prior to exercise requiring high levels of muscle force. Before exercise that requires high muscular forces, individuals may perform dynamic, sport-specific exercises to increase blood flow, metabolic activity, temperature, and compliance of the muscle.

Explosive force training was ineffective at enhancing muscle twitch characteristics, neural drive, or RT in young or old women. It did enhance peak muscle force in both young and old, modulated through a reduction in antagonist coactivation. Older participants showed less of an improvement in the rate of torque development and contractile impulse than young, indicating either that this sample of older women had a reduced capacity to develop muscle power or that the 8-wk isokinetic resistance training program used in this study was not a sufficient stimulus for adaptation.

There is a well-conceived notion that rate of recovery from strenuous exercise gets slower with age. However, it is unclear whether older adults who exercise habitually demonstrate slower rates of recovery. We determined whether older adults who are physically active demonstrate slower rates of recovery from unaccustomed strenuous exercise compared with younger peers. Healthy young sedentary (n=10, 28±2 years), young endurance-trained (n=15, 27±2 years), and older endurance-trained (n=14, 58±2 years) men and women were studied. Participants performed 45 min of downhill running at 65% of their maximal oxygen consumption. Visual analog pain scores of muscle groups increased at 24, 48, and 72 h in all three groups (p<0.05), and changes in the muscular pain scale of the legs was smaller in the older trained group than in the young trained group. Maximum isometric strengths at 90° decreased in all groups at 24 h, but the recovery rates were not different at 72 h among the groups. Plasma creatine kinase activity and myoglobin concentration increased at 24 h following downhill running and returned to baseline at 48 h in both the young and older trained groups. The present findings are not consistent with the prevailing notion that older trained adults have a slower rate of recovery from strenuous exercise.

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