Journal of strength and conditioning research
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J Strength Cond Res · Feb 2013
Acute neuromuscular and endocrine responses and recovery to single-session combined endurance and strength loadings: "order effect" in untrained young men.
The purpose of this study was to investigate acute neuromuscular and endocrine responses and recovery to a single session of combined endurance and strength loading using 2 loading orders. Forty-two men were demographically matched to perform a single session of combined endurance + strength (E + S) or strength + endurance (S + E) loading. The strength loading was conducted on a leg press and included sets of power, maximal strength, and hypertrophic loads with an overall duration of 30 minutes. ⋯ Whereas no significant acute responses were found in concentrations of serum testosterone (T) and thyroid-stimulating hormone in the 2 loading conditions, concentrations of T were significantly reduced in E + S during recovery at 24 hours (-13%, p < 0.05) and 48 hours (-11%, p = 0.068), but not in S + E, and concentrations of thyroid-stimulating hormone significantly reduced after both loading conditions (24 hours: E + S, -32%, p < 0.001; S + E, -25%, p < 0.01; 48 hours: E + S, -25%, p < 0.001; S + E, -18%, p < 0.01). The loading conditions in this study showed that neuromuscular performance recovered already within 2 days, whereas endocrine function, observed particularly by decreased concentrations in serum T after the E + S loading order, remained altered still after 48 hours of recovery. These results emphasize the different needs for recovery after 2 loading orders.
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J Strength Cond Res · Feb 2013
Changes in creatine kinase and cortisol in National Collegiate Athletic Association Division I American football players during a season.
The purpose of this study was to track creatine kinase (CK) and serum cortisol over an American college football season starting with the preseason practice. A secondary purpose was to observe changes in basic clinical chemistries. Twenty-two National Collegiate Athletic Association Division I football players (age: 20.4 ± 1.1 years, height: 188.27 ± 8.3 cm, weight: 115.8 ± 29.7 kg) volunteered to participate in this study. ⋯ Such data demonstrate that changes in muscle damage and adrenal cortical stress over the season are minimal, yet large individual variations can be observed. Management of these variables appears to be related to optimal strength and conditioning and sports medicine programs. Thus, the greater concerns for student-athlete safety in the sport of American football are related to preventing sudden death, traumatic injury, and managing concussion syndromes.