Bakgrund: Studier visar ett starkt samband mellan sprintprestation på bar mark och styrka i konventionella knäböj. Knäböj återfinns även i många styrkeprogram för hockeyspelare, men en potentiell nackdel med övningen är att den utsätter ländryggen för höga kompressionskrafter, något som minskar om man i stället utför en så kallad frontböj. Författaren av den här uppsatsen saknar kännedom om huruvida forskning finns gällande ett potentiellt samband mellan frontböj och sprintprestation på is. Skulle ett sådant samband finnas kan frontböj vara en alternativ övning till konventionella knäböj, detta för att minska belastningen på ländryggen utan att göra avkall på prestation. Syfte: Att avgöra om maxstyrkan i frontböj och vertikal hopphöjd korrelerar med sprintprestationen på is, hos manliga juniorhockeyspelare på elitnivå. Metod: Experimentiell studiedesign. Tretton ishockeyspelare på juniorelitnivå (ålder 17,1 ± 1,1 år; längd = 180,8 ± 7,8 cm; kroppsvikt 79,5 ± 8,8 kg) testades för maximal styrka i frontböj, vertikal hopphöjd och sprintprestation (0-10 meter) på is. Resultat: Pearson´s korrelation visade ett signifikant måttligt samband mellan maximal styrka i frontböj och sprintprestation på is (r = - 0,55, p = 0,050) samt mellan vertikalhopp (CMJ) och sprintprestation på is (r = - 0,67, p = 0,012). Det var ingen signifikant korrelation mellan 10 meter sprint och kvoten 1RM/kroppsvikt (r = - 0,48, p = 0,095). Konklusion: Den här studien pekar mot ett starkare samband mellan hopprestation och sprintprestation på is än mellan maximal styrka och sprintprestation, även om skillnaden inte är signifikant i den här studien.

This study examined and compared static, countermovement, and rebound-type drop jumps from the upper and lower extremities among USA Junior National Team male gymnasts. Twenty-one gymnasts performed two repetitions each of upper (UE) and lower extremity (LE) static (SJ), countermovement (CMJ), and drop (DJ) jumps on a force platform. Average measures of maximum jump height (MXHT), peak force (PF), rate of force development (RFD), and peak power (PP) were calculated for analysis. In addition, sample-specific allometric scaling was used to scale PF and PP. Four 2x3 repeated measures ANOVAs were calculated for analyses. Statistically significant main effects were observed for UE vs LE for MXHT, PF, RFD, and PP (all p < 0.001). Statistically significant main effects for jump-type were also observed: MXHT, PF, RFD, and PP (all p < 0.001). Finally, statistically significant extremities x jump-type interaction effects were obtained for MXHT, PF, RFD, and PP (all p < 0.001). These gymnasts showed better performances in CJs relative to SJs, but performances were unexpectedly poorer in the DJs. Despite using rebound-type jumps in tumbling and vaulting with UE and LE, the DJs did not appear to capture the athletes’ stretch-shortening cycle skill or may reflect poor stretch-shortening cycle skill.

Suchomel, TJ, Wright, GA, Kernozek, TW, and Kline, DE. Kinetic comparison of the power development between power clean variations. J Strength Cond Res 28(2): 350- 360, 2014-The purpose of this study was to compare the power production of the hang clean (HC), jump shrug (JS), and high pull (HP) when performed at different relative loads. Seventeen men with previous HC training experience, performed 3 repetitions each of the HC, JS, and HP at relative loads of 30, 45, 65, and 80% of their 1 repetition maximum (1RM) HC on a force platform over 3 different testing sessions. Peak power output (PPO), peak force (PF), and peak velocity (PV) of the lifter plus bar system during each repetition were compared. The JS produced a greater PPO, PF, and PV than both the HC (p > 0.001) and HP (p > 0.001). The HP also produced a greater PPO (p > 0.01) and PV (p > 0.001) than the HC. Peak power output, PF, and PV occurred at 45, 65, and 30% 1RM, respectively. Peak power output at 45% 1RM was greater than PPO at 65% (p = 0.043) and 80% 1RM (p = 0.004). Peak force at 30% was less than PF at 45% (p = 0.006), 65% (p > 0.001), and 80% 1RM (p = 0.003). Peak velocity at 30 and 45% was greater than PV at 65% (p > 0.001) and 80% 1RM (p > 0.001). Peak velocity at 65% 1RM was also greater than PV at 80% 1RM (p > 0.001). When designing resistance training programs, practitioners should consider implementing the JS and HP. To optimize PPO, loads of approximately 30 and 45% 1RM HC are recommended for the JS and HP, respectively.

Gymnastics tumbling has occurred on large spring floor apparatuses for several decades. The spring floors have used a variety of elastic materials and designs to provide an increased take-off velocity and a forgiving landing surface. The purpose of this study was to assess the efficacy of a standard cylindrical spring (10.7 cm x 5 cm diameter, 9 coils) and a modified spring (10.7 cm, 5 cm widening to 6.7 cm diameter, 9 coils) in tumbling take-offs. Specifically, take-off foot contact durations and center of mass (COM) velocities from female gymnasts (14.8±2.8 y, 159.0±7.2 cm, 49.3±7.1 kg) were measured. Gymnasts performed two trials each of a round off, flic flac, to a layout rearward somersault on each spring-type attached to a tumbling strip (12.19m x 2.41m). Data were acquired via a ViconTM kinematic system using 43 markers and 10 cameras at 200 Hz. Data were found to be reliable across trials. Analysis consisted of two, 2x3 repeated measures ANOVAs. The results showed no statistical differences between spring-types in terms of contact durations or COM component velocities. Spring-type design differences may lead to disparate spring constant and frequency effects, however, these effects of may be overwhelmed by the influences of gymnast skill, matting, carpet, and the wood and fiberglass laminate panels.

The purpose of this investigation was to examine the relationships between measures ofmaximal isometric force (peak force [PF]), rate of force development (RFD), vertical jump performance (VJ) and 1-repetition maximum (1RM) strength in recreationally trained men. The subjects in this study were 26 men ([mean ± SD]: age 22± 1 years; height 175 ± 7 cm; mass 90 ± 10 kg). They were tested for PF using the isometric midthigh pull exercise. The 1RM for the squat and bench press exercise were determined as a measure of dynamic strength. Explosive strength was measured as RFD from the isometric force-time curve. Correlations between the variables were calculated using Pearson product moment correlation coefficient. There was a nearly perfect correlation between measures of PF and 1RM squat (r = 0.97, p < 0.05) and 1RM bench press (r = 0.99, p < 0.05). The correlations were very strong between VJ and PF (r = 0.72, p < 0.05) and 1RM bench press (r = 0.70, p < 0.05). There were also strong correlations between VJ and 1RM squat (r = 0.69, p < 0.05). There were no significant correlations with RFD. The results showed that isometric maximum strength determined during the isometric midthigh pull test correlated well with 1RM and VJ testing. However, RFD measured during the same test did not appear to correlate as well with other measures. The isometric midthigh pull provides an efficient method for assessing strength in recreationally trained individuals. Practioners wishing to obtain performance data related to maximum strength may wish to consider isometric testing as a less time intensive method of testing.

The primary objective of this study was to analyze the relationship between testosterone levels and vertical jumping performance in elite men and women athletes. The secondary objective was to verify whether testosterone levels and vertical jumping performance were different in men and women athletes and if those measurements were different between different athletic groups. Seventy (22 women and 48 men) elite athletes in track and field (sprinters), handball, volleyball, and soccer competing at national and international levels participated in the study. After 10 hours of fasting and 1 day of rest, blood samples were drawn from the antecubital vein for determining testosterone levels. Vertical jumping tests consisted of countermovement jumps conducted on a resistive platform connected to a digital timer. Resting testosterone levels in women were 9.5% of those of the men (respectively 0.62 ± 0.06 ng·ml-1 and 6.49 ± 0.37 ng·ml-1; p < 0.001). Countermovement jump performance was significantly different between women and men athletes, with women's jumping ability 86.3% of that of men (p < 0.001). A significant positive relationship was identified between testosterone levels and vertical jump performance when all data where considered (r = 0.61, p < 0.001, n = 70).

The purpose of this study was to examine the effects of vertically oriented resistance training on golf driving performance. Ten Division-I collegiate golfers completed two resistance training sessions per week for 10 weeks during the fall tournament season. Pre- and post-training assessments of strength-power and golf performance were compared. To assess strength-power, jump height, peak force, and peak power were measured from static and countermovement vertical jumps; peak force and rate of force development from 0 to 250 ms were measured from an isometric mid-thigh pull. Golf performance was assessed in terms of ball launch speed, spin rate, carry yardage, and total yardage, averaged from five shots using a driver. Following training, all measures of strength-power improved, with countermovement jump peak power improving significantly (p < 0.00625). The golf performance assessment indicated significant increases (p < 0.0125) in ball speed, carry yardage, and total yardage. These results suggest that vertically oriented resistance training can improve golf driving performance.

A great deal of research has shown decrements in force and power following static stretching. There has been little research investigating the acute effects of static stretching of the antagonist on the expression of strength and power. The purpose of this study was to investigate the effects of static stretching of the antagonist muscles on a variety of strength and power measures. Sixteen active males were tested for vertical jump height and isokinetic torque production in a slow knee extension (KES) at 60°/s and a fast knee extension (KEF) at 300°/s. Electromyography was taken during knee extension tests for the vastus lateralis and the biceps femoris muscles. Participants performed these tests in a randomized counterbalanced order with and without prior antagonist stretching. All variables for stretching and non-stretching treatments were compared using paired t tests at an alpha of .05. Paired samples t tests revealed a significant (p = .034) difference between stretch KEF and non-stretch KEF conditions. There was no significant (p > .05) difference between KES stretch and non-stretch conditions. Vertical jump height was significantly (p = .011) higher for the stretching treatment than the non-stretching treatment. Vertical jump power was also significantly higher (p = .005) in the stretch versus the non-stretch condition. Paired samples t test indicated no significant (p > .05) difference between testing conditions for electromyography, represented as a percentage of maximal voluntary contraction (MVC). These results suggest that stretching the antagonist hamstrings prior to high speed isokinetic knee extension increases torque production. It also demonstrated that stretching the hip flexors and dorsi flexors may enhance jump height and power. Practitioners may use this information to acutely enhance strength and power performances.

No description available.

The purposes of this dissertation were to examine common athlete training and monitoring practices in men’s collegiate soccer and to report the programming strategies and monitoring outcomes for an NCAA Division I men’s collegiate soccer team whose coaching and sport science staff collaborated on a daily basis. The following are the major findings of the dissertation: Study 1 – Coaches from all divisions of play responded to a custom survey. A majority of coaches developed an in-season training plan that varied both daily and weekly volume and intensity. One-third of the coaches performed no athlete monitoring, and a number of coaches performed purely subjective monitoring of training load and fatigue. Common athlete monitoring tools included sport performance, self-report questionnaires, and physical performance tests. Most coaches believed their athletes did not change or improved in all aspects of performance, while injuries were a mix of new and recurrent. Study 2 – Statistical differences in training load were found between each phase of the season, and training load variation was found with respect to the number of days before a match. Phasic training loads were highest during the pre-season and non-conference portions of the season and decreased significantly during conference play and the post-season. The daily training load values reflected the player groups’ match involvement and therefore led to different loading strategies between the groups. Study 3 – No statistically significant decreases in squat jump height occurred across the season, although a moderate practical decline occurred following the pre-season. The correlation between training load and squat jump height were statistically non-significant, while the cross-correlation was significant. The athlete monitoring program was successful in managing the athletes’ neuromuscular fatigue across the season as evidenced by the maintenance of squat jump height and positive relationship between training load and changes in squat jump height. Coach education on the importance of athlete training load and fatigue monitoring is imperative. Collaboration between coaching and sport science staffs in conjunction with an athlete monitoring program can ensure variation in training load and can help manage athlete fatigue across a competitive season.