Anthropometric and performance changes in male college 15s Rugby Union student-athletes over 52 weeks using in-person training and online training supervision.

BACKGROUND: Although the physiological demands on 15s Rugby Union (RU) players have increased, researchers have suggested that the anthropometric and performance data from developing male college-age RU student-athletes remain limited. This prospective longitudinal repeated measures study aimed to examine the anthropometric and performance changes of male college-age New Zealand Rugby Otago Rugby Football Union (NZRORFU) Academy student-athletes (student-athletes), using in-person and online training supervision (IPTS and OTS, respectively). METHODS: NZRORFU recruited 20 student-athletes (aged 19 to 21 years) and nine were monitored over 52 weeks. During weeks 1 through 35 (in-season), the student-athlete's weekly schedule included 25 hours of IPTS. During the remaining 17 weeks (off-season), the student-athletes followed individualized training programs with OTS. Data were collected on two anthropometric variables and nine performance variables. RESULTS: Over the 52 weeks, using IPTS and OTS, led to increases in both anthropometric measurements with simultaneous significant performance improvements in vertical jump/lower-body power (7.1%, P=0.005, 95% confidence interval (95% CI) 54.4, 63.5), Cohen's effect size (ES) =medium, upper-body strength, bench-press (17.3%, P=0.005, 95% CI 107.4, 127.6, ES=large), and bench-pull (6.1%, P=0.034, 95% CI 90.4, 96.6, ES=large). Furthermore, performance improvements were observed in two anaerobic endurance variables, however, acceleration and speed results were slower. CONCLUSIONS: The use of IPTS and OTS for 52 weeks resulted in increases in body weight and skinfolds with concurrent significant improvements in the performance of VJ/lower-body power and upper-body strength, but changes in each performance variable occurred at different periods.

Functional knee brace use for 21 h leads to a longer duration to achieve peak vertical ground reaction forces and the removal of the brace after 17.5 h results in faster loading of the knee joint.

PURPOSE: To investigate the landing strategies used after discontinuing and continuing the use of a functional knee brace (FKB) while performing a drop jump. METHODS: Following published methodology and power analysis, 23 uninjured male athletes, mean age of 19.4 ± 3.0 years, performed seven tests, during three test conditions (nonbraced, braced and removed brace or continued brace use), over 6 days of 12 testing sessions (S) for a total of 38.5 h. Each subject was provided with a custom-fitted FKB. This study focuses on the single leg drop jump kinetics during S12 when subjects were randomly selected to remove the FKB after 17.5 h or continued use of FKB. The time to peak vertical ground reaction forces (PVGRF) and PVGRF were recorded on landing in eight trials. RESULTS: After brace removal, a significantly shorter mean time to PVGRF was recorded (9.4 ± 22.9 msec (3.9%), p = 0.005, 95% confidence interval (95% CI): -168.1, 36.1), while continued brace use required a nonsignificant (n.s.) longer mean duration to achieve PVGRF (19.4 ± 53.6 msec (8.9%), n.s., 95% CI: -49.7, 73.4). No significant mean PVGRF difference was found in brace removal (25.3 ± 65.8 N) and continued brace use (25.1 ± 23.0 N). CONCLUSION: Removal of FKB after 17.5 h of use led to a significantly shorter time to achieve PVGRF, while continued brace use for 21 h required a longer duration to achieve PVGRF, suggesting faster and slower knee joint loading, respectively. Understanding the concerns associated with the use of FKB and the kinetics of the knee joint will assist clinicians in counselling athletes about the risks and benefits of using an FKB. LEVEL OF EVIDENCE: Level II.

Functional knee brace use effect on peak vertical ground reaction forces during drop jump landing.

PURPOSE: The aim of the study was to investigate the landing strategies used by non-injured athletes while wearing functional knee braces (FKB, BR condition) during a drop jump task compared with non-injured, non-braced (NBR condition) subjects and also to ascertain whether accommodation to a FKB was possible by non-injured BR subjects. METHODS: Twenty-three healthy male provincial and national basketball and field hockey athletes (age, 19.4 ± 3.0 years) were tested. Each subject was provided with a custom-fitted FKB. Five NBR testing sessions were performed over 3 days followed by five BR testing sessions also over 3 days, for a total of 17.5 h of testing per condition. Each subject performed eight trials of the drop jump task during each testing session per condition. Single-leg peak vertical ground reaction forces (PVGRF) and the time to PVGRF were recorded for each NBR and BR trail. RESULTS: The BR group mean PVGRF at landing was significantly lower (1,628 ± 405 N, 2.1 ± 0.5 BW versus 1,715 ± 403 N, 2.2 ± 0.5 BW, F (1,22) = 6.83, P = 0.01) compared with NBR subjects, respectively. The group mean time to PVGRF was not statistically longer during the BR condition (F (1,22) = 0.967, P = 0.3). Further, an accommodation trend was noted as percent performance difference decreased with continued FKB use. CONCLUSIONS: The significantly lower group mean PVGRF while using a FKB could keep traumatic forces from reaching the ACL until the active neuromuscular restraints are activated to provide protection to the knee joint ligaments. Also, accommodation to FKB is possible after approximately 14.0 h of brace use. The results of this paper will assist clinicians in providing information to their patients regarding a FKB ability to offer protection to an ACL-deficient knee or to address concerns about early muscle fatigue, energy expenditure, heart rate, and decrease in performance level. LEVEL OF EVIDENCE: Prospective study, Level I.

Performance of healthy braced participants during aerobic and anaerobic capacity tasks.

CONTEXT: Knee braces were introduced in sports approximately 30 years ago. However, the effects of a functional knee brace (FKB) on aerobic and anaerobic performance after fatigue are unknown. OBJECTIVE: To investigate whether FKB use in noninjured participants hindered performance during aerobic (Léger beep test) and anaerobic (repeated high-intensity shuttle test [RHIST]) tasks. DESIGN: Crossover study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: Twenty-seven healthy male provincial and national basketball and field hockey athletes (age = 19.4±3.0 years, range, 17-26 years; height = 182.6±6.8 cm, range, 168-196 cm; mass = 80.0±9.1 kg, range, 66-108 kg). INTERVENTION(S): Each participant was provided a custom-fitted FKB and performed 5 nonbraced (NBR) testing sessions over 3 days, followed by 5 braced (BR) testing sessions over 3 days, for a total of 17.5 hours of testing per condition. During each testing session, participants performed 1 trial of the Léger beep test and 1 trial of the RHIST in each condition. MAIN OUTCOME MEASURE(S): Predicted maximal oxygen consumption (Vo(2) max) and time performance measures were recorded for each NBR and BR trial. RESULTS: Initial performance levels were lower for BR than NBR for both the Léger beep test (BR = 44.3 mL/kg/min, NBR = 47.3 mL/kg/min; F(1,26) = 8.726; P = .007) and the RHIST (BR = 16.5 seconds, NBR = 16.2 seconds; F(1,26) = 13.98, P = .001). However, with continued FKB use, the aerobic performance measure remained higher for only the first 2 BR testing sessions (NBR = 46.9 mL/kg/min, BR = 42.4 mL/kg/min; F(3.0,79.8) = 4.95, P = .003). For the anaerobic test, no performance difference was noted between the testing conditions (NBR = 16.2 seconds, BR = 16.4 seconds; P = .7), whereas fatigue levels were lower during BR testing sessions (NBR = 33%, BR = 31%). After 14.0 hours of FKB use, performance levels were almost equal between the testing conditions (NBR = 47.6 mL/kg/min, BR = 46.1 mL/kg/min). CONCLUSIONS: We found an initial decrement in performance when the FKB was used during an aerobic or anaerobic task. However, after 14.0 hours of FKB use, accommodation to the FKB was possible.

Effect of functional knee brace use on acceleration, agility, leg power and speed performance in healthy athletes.

OBJECTIVES: To investigate performance levels and accommodation period to functional knee brace (FKB) use in non-injured braced subjects while completing acceleration, agility, lower extremity power and speed tasks. DESIGN: A 2 (non-braced and braced conditions) × 5 (testing sessions) repeated-measures design. METHODS: 27 healthy male athletes were provided a custom fitted FKB. Each subject performed acceleration, agility, leg power and speed tests over 6 days; five non-braced testing sessions over 3 days followed by five braced testing sessions also over 3 days. Each subject performed two testing sessions (3.5 h per session) each day. Performance levels for each test were recorded during each non-braced and braced trial. Repeated measures analysis of variance, with a post hoc Tukey's test for any test found to be significant, were used to determine if accommodation to FKB was possible in healthy braced subjects. RESULTS: Initial performance levels were lower for braced than non-braced for all tests (acceleration p=0.106; agility p=0.520; leg power p=0.001 and speed p=0.001). However, after using the FKB for approximately 14.0 h, no significant performance differences were noted between the two testing conditions (acceleration non-braced, 0.53±0.04 s; braced, 0.53±0.04 s, p=0.163, agility non-braced, 9.80±0.74 s; braced, 9.80±0.85 s, p=0.151, lower extremity power non-braced, 58±7.4 cm; braced, 57±8.1 cm, p=0.163 and speed non-braced, 1.86±0.11 s; braced, 1.89±0.11 s, p=0.460). CONCLUSIONS: An initial decrement in performance levels was recorded when a FKB is used during an alactic performance task. After 12.0-14.0 h of FKB use, performance measures were similar between the two testing conditions.

The potential role of prophylactic/functional knee bracing in preventing knee ligament injury.

It is estimated that knee injuries account for up to 60% of all sport injuries, with the anterior cruciate ligament (ACL) accounting for almost half of these knee injuries. These knee injuries can result in high healthcare costs, as an ACL injury is often associated with surgery, long and costly rehabilitation, differing degrees of impairment and potential long-term consequences such as osteoarthritis. The interest in ACL injury prevention has been extensive for the past decade. Over this period, many ACL (intrinsic and extrinsic) injury risk factors have been identified and investigated by numerous researchers. Although prevention programmes have shown potential in decreasing knee ligament injuries, several researchers have suggested that no conclusive evidence has been presented in reducing the rate and/or severity of ACL injuries during sporting competition. Knee braces have been available for the last 30 years and have been used to assist individuals with ACL-deficient and ACL-reconstructed knees. However, research is limited on the use of knee braces (prophylactic and functional) to potentially prevent knee ligament injury in the non-injured population. One possible explanation for the limited research could be that the use of these devices has raised concerns of decreased or impaired athletic performance. In summary, the review of subjective and some objective publications suggests that a functional knee brace may offer stability to an ACL-deficient knee joint; however, research is limited on the use of a knee brace for prophylactic use in non-injured athletes. The limited research could be a result of fear of performance hindrance that has led to poor knee brace compliance.

The science of softball: implications for performance and injury prevention.

Whilst the sport of softball has achieved worldwide popularity over the last 100 years, a consideration of the scientific principles underpinning softball is in its infancy. It is clear that the various motor skills associated with softball, such as pitching, batting and fielding, place considerable perceptual and physical demands upon players. Each of these skill categories are examined in more detail by reviewing the biomechanical principles associated with skilled performance. For pitching, a certain amount of information can be gleaned from baseball research; however, the underarm technique required by softball places the highest loads on the arm and shoulder during the accelerative, downward phase of the swing. Kinematic analyses of the bat swing suggest that elite batters have approximately 200 ms to decide whether to swing, and approximately the same duration to complete the swing (resulting in reported bat speeds of up to 40 m/sec). The research conducted on fielding has been limited to a consideration of throwing styles adopted in games. A variety of throwing techniques are adopted in the course of a typical game but elite players commonly adopt a sidearm technique when returning to base as quickly as possible. Data obtained from the National Athletic Training Association indicate a similar level of injury incidence in softball as in baseball. Approximately 17% of injuries are experienced by the pitcher and approximately 25% of all injuries are located in the forearm/wrist/hand joint segments. Sports science and sports medicine research have the potential to contribute significantly to performance enhancement and injury prevention in the future.