Journal of strength and conditioning research
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J Strength Cond Res · Dec 2009
Comparative StudyThe effect of chronological age and gender on the development of sprint performance during childhood and puberty.
The purpose of the present study was to examine the effect of chronological age and gender on speed development during different sprinting phases in children and adolescents of both genders. The sample consisted of 360 sedentary pupils aged between 7 and 18 years, with 15 pupils representing each subgroup. The 30-m sprint speed was measured with photocells every 10 m. ⋯ Furthermore, the performance on each sprint phase is uniformly affected by the chronological age. Boys run faster than girls in all running phases, and the span between genders increases after the age of 15 years. It is useful that coaches take these findings into consideration when evaluating children in sprint performance.
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J Strength Cond Res · Dec 2009
Electromyographic analysis of the gluteus medius in five weight-bearing exercises.
Weight-bearing exercises are frequently used to train and strengthen muscles of the hip. These exercises have been advocated in the rehabilitation of a variety of hip and knee dysfunctions. Limited evidence is available to describe the level of muscle activation occurring with specific weight-bearing exercises. ⋯ Single limb stance places more demands on the gluteus medius than double limb stance, whereas single limb squats are more demanding than single limb stance. Although exercises performed on an Airex cushion produced greater EMG values as compared with a firm surface, the difference was not statistically significant. The results, however, suggest that if the goal is to increase the challenge to the gluteus medius, dynamic, single limb exercises performed on unstable surfaces, such as a balance cushion, may place greater demands on the gluteus medius than similar exercises performed on stable surfaces.
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J Strength Cond Res · Oct 2009
Quantifying differences in the "fat burning" zone and the aerobic zone: implications for training.
The primary objective of this study was to examine the relationship of the "fat burning" and aerobic zones. Subjects consisted of 36 relatively fit runners (20 male, 16 female) who completed a maximal exercise test to exhaustion on a motor-driven treadmill. The lower and upper limit of the "fat burning" zone was visually assessed by examining each individual graph. ⋯ Maximal fat oxidation occurred at 54.2% maximal oxygen uptake (VO2max). However, the great variability in response between individuals would preclude the prediction of both the "fat burning" zone and MFO, indicating a need for measurement in the laboratory. If laboratory testing is not possible, the practitioner or subject can be reasonably confident MFO lies between 60.2% and 80.0% of the maximal heart rate.
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The purpose was to test the validity of a nomogram to predict performance at distances ranging from the 10 km to the marathon. Official running rankings of the French Athletics Federation for the men's 10 km, 20 km, and marathon were scrutinized from 2002 to 2006. Performances of runners who competed in the 3 distances during the same year were noted (n = 330). ⋯ These results support the validity of the nomogram to predict performance on 10 km, 20 km, and marathon from the performance at 2 other distances. The accuracy of predictions is better when performance is interpolated. Given their validity and accuracy, interpolated predictions of the nomogram may be used to prescribe realistic training intensities during tempo runs, but also to determine the optimal strategy during the race.
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Hoffman, JR, Kraemer, WJ, Bhasin, S, Storer, T, Ratamess, NA, Haff, GG, Willoughby, DS, and Rogol, AD. Position stand on Androgen and human growth hormone use. J Strength Cond Res 23(5): S1-S59, 2009-Perceived yet often misunderstood demands of a sport, overt benefits of anabolic drugs, and the inability to be offered any effective alternatives has fueled anabolic drug abuse despite any consequences. ⋯ The use of anabolic drugs to enhance athletic performance has become a major concern for professional sport organizations, sport governing bodies, and the federal government. It is the belief of the NSCA that through education and research we can mitigate the abuse of androgens and hGH by athletes. Due to the diversity of testosterone-related drugs and molecules, the term androgens is believed to be a more appropriate term for anabolic steroids.