Change in Femoral Cartilage Cross-Sectional Area After Aerobic and Resistance Exercise.

We compared the immediate response and recovery of femoral cartilage morphology following aerobic or resistance exercise to a control condition. Fifteen healthy young males (23.9 years; 170.1 cm; 69.7 kg) visited the laboratory three separate days and randomly performed one of the 30-min exercise aerobic exercises (treadmill running), resistance exercises (leg presses, back squats, and knee extensions), or seated rest as the control, each followed by the 50-min recovery. Ultrasonographic images of the femoral cartilage cross-sectional area (CSA) were obtained before and after exercise and every 5 min thereafter. To test exercise effects over time, a mixed model analysis of variance and Tukey-Kramer post-hoc tests were performed (p<0.05). The femoral cartilage CSA was different (condition×time: F34,742=4.30, p<0.0001) and the femoral cartilage CSA was decreased after the aerobic (-5.8%, p<0.0001) and the resistance (-3.4%, p=0.04) exercises compared to the pre-exercise levels. Deformed femoral cartilage CSA took 35 and 10 min to return to the pre-exercise levels after aerobic and resistance exercises (p+>+0.09), respectively. Thirty minutes of moderate exertion performing aerobic or resistance exercises immediately reduced the femoral cartilage CSA. A rest period ranging from 10 to 35 min was required for cartilage recovery after weight-bearing exercises.

A warm-up strategy with or without voluntary contraction on athletic performance, lower-leg temperature, and blood lactate concentration.

It is unclear whether temperature-related warm-up effects can be accomplished by passive warm-up (e.g., by external heat). Therefore, this study compared the effects of two different warm-up protocols with and without voluntary contraction on subsequent sprinting and jumping performance. Eighteen healthy male collegiate students (23.3 ± 2.4 years, 173.8 ± 7.2 cm, 70.5 ± 9.3 kg) randomly experienced 10 min of active (jogging on a treadmill; belt speed: 9.0 km/h at a 1% incline) and passive warm-up (lying down in the warm-up chamber; inner ambient temperature set at 35°C) protocols, followed by ten sets of intermittent exercises in two separate sessions. Athletic performance, lower-leg muscle temperature, and blood lactate concentration were statistically compared using analysis of variance with Tukey-Kramer post-hoc comparisons. Cohen's d effect sizes (ES) were also calculated. There was no warm-up protocol effect over time on 20 m sprint times (condition × time: F9,323 = 1.26, p = 0.25). Maximal vertical jump heights were different (condition × time: F9,323 = 2.0, p = 0.04) such that subjects who performed the active warm-up protocol jumped higher (51.4 cm) than those who did the passive warm-up (49.2 cm, p = 0.04). There was a warm-up protocol effect over time on lower-leg muscle temperature (condition × time: F12,425 = 13.99, p<0.0001) in that there was a 5.5% and 5.8% increase after active (32.8 to 34.6°C, ES = 2.91) and passive (32.9 to 34.9°C, ES = 3.28) warm-up protocols, respectively. Blood lactate concentration was different (condition × time: F2,85 = 3.61, p = 0.03) since the values at the post-warm-up measurements were different between warm-up conditions (active: 4.1 mmol/L; passive: 1.5 mmol/L, p = 0.004, ES = 1.69). Subsequent sprint and jump performance did not differ between the duration- and muscle temperature-matched active and passive warm-up protocols. Non-thermal effects from the warm-up activity may be minimal for sprinting and jumping performance in recreationally active males.

Comparison of 4 Different Cooldown Strategies on Lower-Leg Temperature, Blood Lactate Concentration, and Fatigue Perception After Intense Running.

CONTEXT: Although active recovery (AR) and cold application is recommended, many people take a shower after exercise. Therefore, a direct comparison between a shower and other recommended methods (AR and/or cold-water immersion) is necessary. To compare immediate effects of 4 postexercise cooldown strategies after running. DESIGN: A crossover design. METHODS: Seventeen young, healthy males (23 y; 174 cm; 73 kg) visited on 4 different days and performed a 10-minute intense treadmill run (5 km/h at a 1% incline, then a belt speed of 1 km/h, and an incline of 0.5% were increased every minute). Then, subjects randomly experienced 4 different 30-minute cooldown strategies each session-AR (10-min treadmill walk + 10-min static stretch + 10-min shower), cold-water walk (10-min shower + 20-min walk in cold water), cold-water sit (10-min shower + 20-min sit in cold water), and passive recovery (10-min shower + 20-min passive recovery). Across the cooldown conditions, the water temperatures for immersion and shower were set as 18 °C and 25 °C, respectively. Lower-leg muscle temperature, blood lactate concentration, and fatigue perception were statistically compared (P < .001 for all tests) and effect sizes (ES) were calculated. RESULTS: The cold-water walk condition (F135,2928 = 69.29, P < .0001) was the most effective in reducing muscle temperature after running (-11.6 °C, ES = 9.46, P < .0001), followed by the cold-water sit (-8.4 °C, ES = 8.61, P < .0001), passive recovery (-4.5 °C, ES = 4.36, P < .0001), and AR (-4.0 °C, ES = 4.29, P < .0001) conditions. Blood lactate concentration (F6,176 = 0.86, P = .52) and fatigue perception (F6,176 = 0.18, P = .98) did not differ among the 4 conditions. CONCLUSIONS: While the effect of lowering the lower-leg temperature was different, the effect of reducing blood lactate concentration and fatigue perception were similar in the 4 cooldown strategies. We suggest selecting the appropriate method while considering the specific goal, available time, facility, and accessibility.