Journal of strength and conditioning research
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J Strength Cond Res · Apr 2010
Comparative StudyAnabolic and catabolic hormones and energy balance of the male bodybuilders during the preparation for the competition.
The purpose of the study was to investigate simultaneous effects of energy balance, caloric intake, and the hormonal anabolic-catabolic balance in bodybuilders prior to competition. Fourteen male bodybuilders took part in an 11-week energy-restricted period to reduce body fat. The subjects were divided into the energy-restricted group (ERG) (n = 7), who were preparing for the competition, or the control group (CG) (n = 7) who continued to train regularly and did not change their dietary or training pattern. ⋯ These data indicate that severe energy restriction to extremely low body energy reserves decreases significantly the concentrations of 3 anabolic pathways despite high protein intake. Monitoring of insulin and IGF-1 concentration is suggested to prevent losses in muscle mass in energy-restricted conditions. Other nutritional strategies might be needed to prevent possible catabolic effect during preparation of bodybuilders to competition.
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J Strength Cond Res · Mar 2010
Randomized Controlled Trial Comparative StudyAcute effects of Flexi-bar vs. Sham-bar exercise on muscle electromyography activity and performance.
This study was conducted to investigate whether the low-frequency (5-Hz) oscillatory vibration-like stimulus, purported to be delivered by exercising with Flexi-bar, acutely affects muscle activation and maximal voluntary contraction (MVC) force. Nine healthy men participated in 2 trials, separated by at least 1 week, during which 4 x 30-second sets of exercise were performed with either the Flexi bar or a Sham bar. Maximal voluntary contraction force for elbow flexion, elbow extension, and knee extension were measured before and after the exercise. ⋯ Knee extension MVC force significantly decreased after Flexi-bar exercise (-3 +/- 7%, p = 0.048) in parallel with reduced RF EMG amplitude (-8 +/- 5%, p = 0.04), but there were no acute residual effects on elbow flexion/extension MVC or arm and VL EMG muscle activity. Using Flexi bar during exercise provoked acute alterations in arm- and leg-muscle EMG parameters and maximum force-generating capacity, indicating greater fatigue development than when exercising with the Sham bar. The results of this study indicate that Flexi bar may therefore be used to impose a stronger training stimulus on the muscle during submaximal exercise.
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J Strength Cond Res · Mar 2010
The reliability and validity of handheld dynamometry for the measurement of lower-extremity muscle strength in older adults.
Lower-extremity muscle strength is important in predicting fall risk in older adults. Handheld dynamometry (HHD) is a tool used to measure isometric muscle strength in the older adult, but few studies have evaluated the utility of HHD for muscle groups beyond knee extension. The purpose of this study was to evaluate the reliability of HHD at the hip, knee, and ankle and to compare HHD strength values to other isometric dynamometry (ID) and to balance and recovery in older adults. ⋯ Hip and knee strength was positively associated to step length and reaction time but not to balance (r = 0.40-0.71; p < 0.05). In conclusion, HHD is a reliable and valid assessment tool for measuring strength at the hip and knee in older adults, and greater strength in these muscles is associated with longer step length and decreased reaction time, which are important components of balance recovery in older adults. HHD can be used as an effective strength measurement tool for the older adult population.
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J Strength Cond Res · Feb 2010
Comparative StudyInitial reliability and validity of the lift-and-raise hamstring test.
The Lift-and-Raise hamstring flexibility test was developed as a field-based assessment to eliminate the effects of individual and developmental differences in arm, leg, and trunk lengths found with the commonly used Sit-and-Reach tests. This study assessed the initial reliability of the prototype instrument and its validity by comparing obtained values from a Cybex Testing and Rehabilitation System. ⋯ A high intraclass correlation coefficient emerged between the 2 testers (r = 0.944) on the Lift-and-Raise instrument and between the Lift-and-Raise test and the Cybex testing protocol (r = 0.891). Based on initial results, the Lift-and-Raise test seems to be a reliable and valid test to measure hamstring flexibility.
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J Strength Cond Res · Jan 2010
Clinical TrialEffects of musical cadence in the acute physiologic adaptations to head-out aquatic exercises.
The purpose of this study was to analyze the relationships between musical cadence and the physiologic adaptations to basic head-out aquatic exercises. Fifteen young and clinically healthy women performed, immersed to the breast, a cardiovascular aquatic exercise called the "rocking horse." The study design included an intermittent and progressive protocol starting at a 90 b.min(-1) rhythm and increasing every 6 minutes, by 15 b.min(-1), up to 195 b.min(-1) or exhaustion. The rating of perceived effort (RPE) at the maximal heart rate achieved during each bout (HRmax), the percentage of the maximal theoretical heart rate estimated (%HRmax), and the blood lactate concentration ([La-]) were evaluated. ⋯ The R4 was 148.13 +/- 17.53 b.min, the RPE@R4 was 14.53 +/- 2.53, the HR@R4 was 169.33 +/- 12.06 b.min, and the %HRmax@R4 was 85.53 +/- 5.72%. The main conclusion is that increasing musical cadence created an increase in the physiologic response. Therefore, instructors must choose musical cadences according to the goals of the session they are conducting to achieve the desired intensity.