A decreased hamstring:quadriceps (H:Q) ratio may put the hamstrings and anterior cruciate ligament (ACL) at increased risk of injury. Therefore, the purpose of this study was to evaluate H:Q ratios of 12 female National Collegiate Athletic Association soccer players, and to test the effects of a 6-week strength training program on these ratios. Each subject completed 2 practice sessions before a pretest. Subjects then completed 6 weeks of strength training that included the addition of 2 hamstring specific exercises, followed by a posttest. Peak torque during concentric and eccentric actions for both hamstrings and quadriceps was measured with an isokinetic dynamometer. Each muscle action was tested at 3 angular velocities in the following order: concentric 240, 180, and 60 degrees x s(-1) and eccentric 60, 180, and 240 degrees x s(-1). The H:Q strength ratio was evaluated using concentric muscle actions (concentric hamstrings:concentric quadriceps). This method is commonly used and is thus called the conventional ratio. Because concentric actions do not occur simultaneously in opposing muscles, a more functional assessment compares eccentric hamstring actions to concentric quadriceps actions. This functional ratio was also analyzed. Mean conventional and functional H:Q ratio data were analyzed using separate analysis of variance procedures with repeated measures on all factors (2 [Test] x 2 [Leg] x 3 [Angular Velocity]). The results revealed a significant main effect for factor (F test) with the functional ratio (p < 0.05) but not for the conventional ratio. The mean functional ratio increased from 0.96 +/- 0.09 in pretest to 1.08 +/- 0.11 in posttest. These results suggest that 6 weeks of strength training that emphasizes hamstrings is sufficient to significantly increase the functional ratio. The functional ratio after training exceeded 1.0, which is specifically recommended for prevention of ACL injuries.

Preactivity stretching is commonly performed by athletes as part of their warm-up routine. However, the most recent literature questions the effectiveness of preactivity stretching. One limitation of this research is that the stretching duration is not realistic for most athletes. Therefore, the purpose of this study was to determine the effects of a practical duration of acute static and ballistic stretching on vertical jump (VJ), lower-extremity power, and quadriceps and hamstring torque. Twenty-four subjects performed a 5-minute warm-up followed by each of the following three conditions on separate days with order counterbalanced: static stretching, ballistic stretching, or no-stretch control condition. Vertical jump was determined with the Vertec VJ system and was also calculated from the ground-reaction forces collected from a Kistler force plate, which also were used to calculate power. Torque output of the quadriceps and hamstrings was measured through knee extension and flexion on the Biodex System 3 Dynamometer at 60 degrees x s(-1). Data normalized for body weight were analyzed using five separate, 3 (stretch condition) x 2 (gender) analysis-of-variance procedures with repeated measures on the factor of stretch condition. The gender x stretch interaction was not significant for any of the four measures, suggesting that the stretching conditions did not affect men and women differently. The results of this study reveal that static and ballistic stretching did not affect VJ, or torque output for the quadriceps and hamstrings. Despite no adverse effect on VJ, stretching did cause a decrease in lower-extremity power, which was surprising. Because of the mixed results, strength coaches would be better served to use dynamic stretching before activity; this has been consistently supported by the literature.

The purpose of this study was to measure the effects of low-frequency, low-impact plyometric training on vertical jump (VJ) and kicking distance in female adolescent soccer players. Sixteen adolescent soccer players were studied (age 13.4 ± 0.5 years) across 14 weeks. The control group (general soccer training only) had 6 subjects, and the plyometric training (general soccer training plus plyometric exercise) group had 10 subjects. All subjects were tested for VJ and kicking distance on 3 occasions: pre-test, 7 weeks, and 14 weeks. Data were analyzed using a 2 (Training) × 3 (Test) analysis of variance (ANOVA) with repeated measures on the factor test. No significant difference in kicking distance was found between groups at pre-test (p = 0.688) or 7 weeks (p = 0.117). The plyometric group had significantly greater kicking distance after 14 weeks (p < 0.001). No significant difference in VJ height was found between groups at pre-test (p = 0.837) or 7 weeks (p = 0.108). The plyometric group had a significantly higher VJ after 14 weeks (p = 0.014). These results provide strength coaches with a safe and effective alternative to high-intensity plyometric training. Based on these findings, to increase lower-body power resulting in increased VJ and kicking distance, strength coaches should implement once-weekly, low-impact plyometric training programs with their adolescent athletes.

Context: Certified athletic trainers can choose different types of external compression (none, Flex-i-Wrap, and elastic wrap) when applying an ice bag to the body. However, which type facilitates the greatest magnitude of tissue cooling is unclear.Objective: To compare the effects of 2 common types of external compression on the magnitude of surface and intramuscular cooling during an ice-bag treatment.Design: Randomized controlled trial. Setting: University research laboratory.Patients or Other Participants: Fourteen college students (10 women, 4 men; age 5 22.4 6 1.8 years, height 5 169.1 6 8.2 cm, mass 5 73.3 6 18.5 kg, skinfold 5 13.14 6 1.61 mm) with previous cryotherapy experience and a posterior lower leg skinfold equal to or less than 15 mm.Intervention(s): On 3 different days separated by 24 to 48 hours, an ice bag was applied to the posterior lower leg surface of each participant for 30 minutes with no compression, with elastic wrap, or with Flex-i-Wrap.Main Outcome Measure(s): Posterior lower leg surface and intramuscular (2 cm) temperatures were recorded for 95 minutes.Results: At 15 minutes, the elastic wrap produced greater surface temperature reduction than no compression (P 5 .03); this difference remained throughout the protocol (P range, .03 to .04). At 30 minutes, surface temperatures were 14.956C, 11.556C, and 9.496C when an ice bag was applied with no external compression, Flex-i-Wrap, and elastic wrap, respectively. Surface temperatures between Flex-i-Wrap and elastic wrap and between Flex-i-Wrap and no compression were never different. At 10 minutes, Flex-i-Wrap (P 5 .006) and elastic wrap (P , .001) produced greater intramuscular temperature reduction than no compression produced; these differences remained throughout the protocol. At 10 minutes, no compression, Flex-iWrap, and elastic wrap decreased intramuscular temperature by 1.346C, 2.466C, and 2.736C, respectively. At 25 minutes, elastic wrap (8.036C) produced greater temperature reduction than Flexi-Wrap (6.656C) (P 5 .03) or no compression (4.636C) (P , .001 ). These differences remained throughout ice application and until 50 minutes after ice-bag removal.Conclusions: During an ice-bag application, external compression with elastic wrap was more effective than Flex-i-Wrap at reducing intramuscular tissue temperature. Elastic wraps should be used for acute injury care.Key Words: intramuscular temperatures, surface temperatures, insulation Key Points N External compression of an ice bag with an elastic wrap provided greater temperature reduction after a 30-minute treatment than did compression with Flex-i-Wrap. N Intramuscular temperature decreases were different but surface temperature decreases were not different between Flex-iWrap and elastic wrap compression.N Intramuscular temperature was lower with compression than with no compression at 10 minutes and was lower with elastic wrap than with Flex-i-Wrap at 25 minutes.N Compression with elastic wrap demonstrated a higher average atmosphere-interface temperature than the other con...

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