Sex Differences in Neck Strength Force and Activation Patterns in Collegiate Contact Sport.

The purpose of this study was to assess changes in cervical musculature throughout contact-heavy collegiate ice hockey practices during a regular season of NCAA Division III ice hockey teams. In this cross-sectional study, 36 (male n = 13; female n = 23) ice hockey players participated. Data were collected over 3 testing sessions (baseline; pre-practice; post-practice). Neck circumference, neck length, head-neck segment length, isometric strength and electromyography (EMG) activity for flexion and extension were assessed. Assessments were completed approximately 1h before a contact-heavy practice and 15 min after practice. For sternocleidomastoid (SCM) muscles, males had significantly greater peak force and greater time to peak force versus females. For both left and right SCMs, both sexes had significantly greater peak EMG activity pre-practice versus baseline, and right (dominant side) SCM time to peak EMG activity was decreased post-practice compared to pre-practice. There were no significant differences for EMG activity of the upper trapezius musculature, over time or between sexes. Sex differences observed in SCM force and activation patterns of the dominant side SCM may contribute to head stabilization during head impacts. Our study is the first investigation to report changes in cervical muscle strength in men's and women's ice hockey players in the practical setting.

Epidemiology of Concussions in High School Boys' Ice Hockey, 2008/09 to 2016/17 School Years.

OBJECTIVE: This study examined the epidemiology of concussions in high school boys' ice hockey during the 2008/09 to 2016/17 school years. DESIGN: Prospective cohort study. Athletic trainers from an average 33 high schools annually reported boys' ice hockey concussion and athlete-exposure (AE) data for the High School Reporting Information Online system. SETTING: Convenience sample of high school boys' ice hockey programs during the 2008/09 to 2016/17 school years. PATIENTS OR OTHER PARTICIPANTS: High school boys' ice hockey players (aged ∼14-18 years). INDEPENDENT VARIABLES: Concussion data on event type, injury mechanism, symptom resolution time, and time loss were obtained. MAIN OUTCOME MEASURES: Concussion rates with 95% confidence intervals (CIs) and distributions were calculated. RESULTS: Overall, 348 concussions were reported in boys' ice hockey during the 2008/09 to 2016/17 academic years, leading to a concussion rate of 0.68/1000 AEs (95% CI, 0.61-0.75). Most occurred in competitions (85.6%), particularly after the first period (72.1% of all competition concussions). Among practice concussions, most occurred after the first hour of practice (60.0%). Most concussions were due to player contact (47.7%) and boards/glass contact (31.9%). Although 69.0% of concussed athletes had symptoms resolve in less than 7 days, only 14.1% returned to activity within a week. CONCLUSIONS: Most concussions occurred within the second and third periods. Preventive strategies that counter an increased risk of concussion due to a greater intensity of gameplay coupled with increased fatigue may be warranted. Moreover, athletes may further benefit from prevention efforts that focus on anticipating impacts during gameplay.

Unexpected Findings from a Pilot Study on Vision Training as a Potential Intervention to Reduce Subconcussive Head Impacts during a Collegiate Ice Hockey Season.

Player-to-player contact is the most frequent head impact mechanism in collegiate ice hockey. Training with three-dimensional multiple-object tracking (3D-MOT) could potentially reduce the quantity and severity of head impacts by enhancing player anticipation of these impacts. The purpose of this study was to evaluate the efficacy of 3D-MOT training to reduce the numbers of head impacts sustained by National Collegiate Athletic Association Division III men's and women's ice hockey players. Collegiate men's and women's ice hockey players (N = 33; men = 17, women = 16) were randomly assigned to a 3D-MOT group (n = 17) or a control (C) group (n = 16). Head impacts were monitored during practices and games, and 3D-MOT training occurred twice per week for 12 weeks throughout one regular season. 3D-MOT forwards sustained head impacts with greater mean peak linear acceleration (3D-MOT = 41.33 ± 28.54 g; C = 38.03 ± 24.30 g) and mean peak rotational velocity (3D-MOT = 13.59 ± 8.18 rad.sec-1; C = 12.47 ± 7.69 rad.sec-1) in games, and greater mean peak rotational velocity in practices versus C forwards (3D-MOT = 11.96 ± 6.77 rad.sec-1; C = 10.22 ± 6.95 rad.sec-1). Conversely, 3D-MOT defensemen sustained head impacts with a mean peak rotational velocity less than that of C defensemen (3D-MOT = 11.54 ± 6.76 rad.sec-1; C = 13.65 ± 8.43 rad.sec-1). There was no significant difference for all other parameters analyzed between 3D-MOT and C groups. Player position may play an important role in future interventions to reduce head impacts in collegiate ice hockey.

Head impact exposures in women's collegiate rugby.

Objectives: To describe the incidence, magnitude, and distribution of head impacts and track concussions sustained in a collegiate level women's rugby season. Methods: Data on head impact incidence and magnitude were collected via Smart Impact Monitors (SIM) (Triax Technologies, Inc., Norwalk, CT) within fitted headbands during practices and games of one competitive season. Magnitude data included peak linear acceleration (PLA) and peak rotational velocity (PRV) measurements and were reported as median [IQR]. Results: Players sustained 120 head impacts ≥15 g (18.1 g - 78.9 g) with 1199 total athlete exposures. In eight games, 67 head impacts were recorded with a mean rate of 0.40 ± 0.22 hits per-player per-match, median PLA of 32.2 g, and PRV of 13.5 rad.sec-1. There were 53 head impacts in 47 practices with a mean rate of 0.05 ± 0.04 hits per-player per-practice, median PLA of 29.8 g and PRV of 15.7 rad.sec-1. Four concussions were reported and monitored. Conclusion: The incidence and magnitude of head impacts in collegiate level women's rugby over one season of practices and games were fewer than those reported in other comparable studies. These findings give insight into the impact burden that female collegiate rugby athletes withstand throughout a competitive season.

Head impacts and cognitive performance in men's lacrosse.

OBJECTIVES: The purpose of this investigation was to record head impacts and assess cognitive function throughout a NCAA Division III men's lacrosse season. METHODS: Fifteen NCAA Div III men's lacrosse players (age = 21.1 ± 1.5 years; height = 179 ± 7.00cm; weight = 80.74 ± 8.00kg) wore Smart Impact Monitors (SIM) (Triax Technologies, Inc., Norwalk, CT) within headbands, in 28 practices and 9 home games of one season. The SIM devices communicated with the Triax Technologies SKYi, which confirmed activated SIMs and obtained data of linear acceleration, rotational acceleration, rotational velocity, direction, and location of each head impact. A minimum threshold of 15g of force was set for head impacts to register with the SIMs. The Comprehensive Trail Making Test and Stroop Color and Word Test were administered at preseason, midseason, and postseason to assess cognitive function performance. RESULTS: There was no significant difference found between all measures of frequency and magnitude of head impacts between games and practices. There was also no significant difference for peak linear acceleration of head impacts between different positions and no significant difference between the magnitude of force and the location of impact on the head. There was a significant increase in CTMT performance from preseason to midseason, from midseason to postseason, and preseason to postseason. There was no significant difference in Stroop test performance throughout the season. CONCLUSION: Subconcussive head impacts in men's lacrosse appear to occur at the same magnitude in practices and games, and do not appear to be position dependent, nor head location dependent. Men's lacrosse athletes' cognitive function as measured by the CTMT, can improve, while cognitive function as measured by the Stroop test remained unchanged.

Comparison of Concussion Rates Between NCAA Division I and Division III Men's and Women's Ice Hockey Players.

BACKGROUND: Examinations related to divisional differences in the incidence of sports-related concussions (SRC) in collegiate ice hockey are limited. PURPOSE: To compare the epidemiologic patterns of concussion in National Collegiate Athletic Association (NCAA) ice hockey by sex and division. STUDY DESIGN: Descriptive epidemiology study. METHODS: A convenience sample of men's and women's ice hockey teams in Divisions I and III provided SRC data via the NCAA Injury Surveillance Program during the 2009-2010 to 2014-2015 academic years. Concussion counts, rates, and distributions were examined by factors including injury activity and position. Injury rate ratios (IRRs) and injury proportion ratios (IPRs) with 95% confidence intervals (CIs) were used to compare concussion rates and distributions, respectively. RESULTS: Overall, 415 concussions were reported for men's and women's ice hockey combined. The highest concussion rate was found in Division I men (0.83 per 1000 athlete-exposures [AEs]), followed by Division III women (0.78/1000 AEs), Division I women (0.65/1000 AEs), and Division III men (0.64/1000 AEs). However, the only significant IRR was that the concussion rate was higher in Division I men than Division III men (IRR = 1.29; 95% CI, 1.02-1.65). The proportion of concussions from checking was higher in men than women (28.5% vs 9.4%; IPR = 3.02; 95% CI, 1.63-5.59); however, this proportion was higher in Division I women than Division III women (18.4% vs 1.8%; IPR = 10.47; 95% CI, 1.37-79.75). The proportion of concussions sustained by goalkeepers was higher in women than men (14.2% vs 2.9%; IPR = 4.86; 95% CI, 2.19-10.77), with findings consistent within each division. CONCLUSION: Concussion rates did not vary by sex but differed by division among men. Checking-related concussions were less common in women than men overall but more common in Division I women than Division III women. Findings highlight the need to better understand the reasons underlying divisional differences within men's and women's ice hockey and the need to develop concussion prevention strategies specific to each athlete population.

Effects of oral creatine and resistance training on myogenic regulatory factor expression.

PURPOSE: This study examined 12 wk of creatine (Cr) supplementation and heavy resistance training on skeletal muscle creatine kinase (M-CK) mRNA expression and the mRNA and protein expression of the myogenic regulatory factors Myo-D, myogenin, MFR-4, and Myf5. METHODS: Twenty-two untrained males were randomly assigned to either a control (CON), placebo (PLC), or Cr (CRT) group in a double-blind fashion. Muscle biopsies were obtained before and after training. PLC and CRT trained thrice weekly using 3 sets of 6-8 repetitions at 85-90% 1-RM on the leg press, knee extension, and knee curl exercises. CRT ingested 6 g.d-1 of Cr for 12 wk while PLC consumed the equal amount of placebo. RESULTS: After training, M-CK mRNA expression, as well as myogenin and MRF-4 mRNA and protein expression, were found to be significantly greater for CRT compared with PLC and CON, whereas PLC was also significantly different from CON (P < 0.05). For Myo-D mRNA and protein, both CRT and PLC were significantly different from CON (P < 0.05), but CRT and PLC were not different from one another. No significant differences were located for Myf5 mRNA or protein (P > 0.05). M-CK mRNA was correlated with myogenin (r = 0.916) and MRF-4 (r = 0.883) protein (P < 0.05). CONCLUSION: When combined with heavy resistance training, Cr supplementation increases M-CK mRNA expression, likely due to concomitant increases in the expression of myogenin and MRF-4. Therefore, increases in myogenin and MRF-4 mRNA and protein may play a role in increasing myosin heavy chain expression, already shown to occur with Cr supplementation.

A Comparison of Thermoregulation With Creatine Supplementation Between the Sexes in a Thermoneutral Environment.

OBJECTIVE: To compare the effect of creatine supplementation on thermoregulation in males and females during exercise in a thermoneutral environment. DESIGN AND SETTING: Male and female subjects participated in 30 minutes of cycle ergometry in nonsupplemented (NS) and creatine-supplemented (Cr) conditions at 70% to 75% of predetermined peak oxygen consumption. SUBJECTS: Ten male and ten female subjects were evaluated with and without creatine supplementation. MEASUREMENTS: Analyses were performed during exercise for core temperature and mean skin temperature using two 2 x 2 x 7 mixed-factorial analyses of variance (ANOVAs). We compared mean differences between NS and Cr conditions and sex for heart rate, systolic blood pressure, and diastolic blood pressure using 3 2 x 2 x 4 mixed-factorial ANOVAs. Three 2 x 2 mixed-factorial ANOVAs were computed to examine differences between sex and conditions for the following variables: nude body weight and blood urea nitrogen before and after exercise and urine specific gravity. RESULTS: Significant time effects were found for core temperature, skin temperature, heart rate, and diastolic blood pressure. Time effect and difference between the sexes for systolic blood pressure were both significant. Differences in nude body weight and blood urea nitrogen before and after exercise were greater for males, but there was no difference between conditions. No significant difference between sex and condition for urine specific gravity was noted. CONCLUSIONS: Short-term creatine supplementation did not affect thermoregulation between the sexes when exercising in a thermoneutral environment. Differences in changes in nude body weight before and after exercise may be due to a higher sweating rate in males versus females. Differences in blood urea nitrogen before and after exercise between the sexes may be due to a reduced glomerular filtration rate coupled with greater muscle creatine breakdown in males.

Isokinetic Hamstrings:Quadriceps Ratios in Intercollegiate Athletes.

OBJECTIVE: To compare the differences in the concentric hamstrings:quadriceps (H:Q) ratio among athletes in different sports at 3 velocities. DESIGN AND SETTING: We measured the H:Q ratio of both knees using the Biodex Pro Isokinetic Device. SUBJECTS: Eighty-one male and female collegiate athletes. MEASUREMENTS: We performed analyses for sport, velocity, and side of body for each sex. To compare the means of the concentric H:Q ratios for mean peak torque and mean total work, a 2 x 3 x 4 mixed-factorial analysis of variance was computed for women and a 2 x 2 x 3 mixed-factorial analysis of variance was computed for men. RESULTS: We observed no significant interactions for men and women for the concentric H:Q ratio for mean peak torque. There was a significant mean difference among velocity conditions and a significant difference for men with respect to velocity. No significant differences were found for side of body or sport. CONCLUSIONS: The H:Q ratio increased as velocity increased. No differences existed for the H:Q ratio for sport or side of body.