Journal of strength and conditioning research
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J Strength Cond Res · Nov 2013
Acute Effects of contract-relax stretching vs. TENS in young subjects with anterior knee pain: a randomized controlled trial.
The aim of this study was to examine the immediate effects on pressure point tenderness, range of motion and vertical jump of contract-relax stretching versus transcutaneous electrical stimulation (TENS) therapy in individuals with anterior knee pain (AKP). Eighty-four subjects with AKP were randomly assigned to one of three different intervention groups: a contract-relax stretching group (n=28), a TENS intervention group (n=28) and a control group (n=28). The participants included in the sample were both sex (37.5% men vs 62.5% women) at mean age of 21 years old, with mean values of height and weight of 169 cm and 64 kg. ⋯ A significant increase pre to post treatment in ROM (p<0.001) was also observed in both treatment groups. In VJ measures, TENS and stretching groups showed significant differences between pre and all post-intervention values (p<0.05), while no significant differences were found in the control group. In conclusion, the results show significant pre-to-post-treatment effects in PPT, ROM and VJ from both contract-relax stretching and TENS in young subjects with AKP.
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J Strength Cond Res · Nov 2013
Pressure pain mapping of the wrist extensors after repeated eccentric exercise at high intensity.
The purpose of this study was to investigate adaptation mechanisms after 2 test rounds consisting of eccentric exercise using pressure pain imaging of the wrist extensors. Pressure pain thresholds (PPTs) were assessed over 12 points forming a 3 × 4 matrix over the dominant elbow in 12 participants. From the PPT assessments, pressure pain maps were computed. ⋯ A lack of hyperalgesia, i.e., no decrease in PPT underlined adaptation after the second test round of eccentric exercise performed 7 days after the initial test round. The present findings showed for the first time that repeated eccentric exercise performed twice over 2 weeks protects the wrist extensor muscles from developing exacerbated pressure pain sensitivity. Thus, the addition of eccentric components to training regimens should be considered to induce protective adaptation.
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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.
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J Strength Cond Res · Aug 2012
Meta AnalysisConcurrent training: a meta-analysis examining interference of aerobic and resistance exercises.
The primary objective of this investigation was to identify which components of endurance training (e.g., modality, duration, frequency) are detrimental to resistance training outcomes. A meta-analysis of 21 studies was performed with a total of 422 effect sizes (ESs). Criteria for the study included were (a) compare strength training alone to strength plus endurance training (concurrent) or to compare combinations of concurrent training; (b) the outcome measures include at least one measure of strength, power, or hypertrophy; and (c) the data necessary to calculate ESs must be included or available. ⋯ Correlational analysis identified significant negative relationships between frequency (-0.26 to -0.35) and duration (-0.29 to -0.75) of endurance training for hypertrophy, strength, and power. Significant relationships (p < 0.05) between ES for decreased body fat and % maximal heart rate (r = -0.60) were also found. Our results indicate that interference effects of endurance training are a factor of the modality, frequency, and duration of the endurance training selected.