RESUMEN
PURPOSE: To assess the relationships between player characteristics (including age, playing experience, ethnicity, and physical fitness) and in-season injury in elite Australian football. DESIGN: Single-cohort, prospective, longitudinal study. METHODS: Player characteristics (height, body mass, age, experience, ethnicity, playing position), preseason fitness (6-min run, 40-m sprint, 6×40-m sprint, vertical jump), and in-season injury data were collected over 4 seasons from 1 professional Australian football club. Data were analyzed for 69 players, for a total of 3879 player rounds and 174 seasons. Injury risk (odds ratio [OR]) and injury severity (matches missed; rate ratio [RR]) were assessed using a series of multilevel univariate and multivariate hierarchical linear models. RESULTS: A total of 177 injuries were recorded with 494 matches missed (2.8±3.3 matches/injury). The majority (87%) of injuries affected the lower body, with hamstring (20%) and groin/hip (14%) most prevalent. Nineteen players (28%) suffered recurrent injuries. Injury incidence was increased in players with low body mass (OR=0.887, P=.005), with poor 6-min-run performance (OR=0.994, P=.051), and playing as forwards (OR=2.216, P=.036). Injury severity was increased in players with low body mass (RR=0.892, P=.008), tall stature (RR=1.131, P=.002), poor 6-min-run (RR=0.990, P=.006), and slow 40-m-sprint (RR=3.963, P=.082) performance. CONCLUSIONS: The potential to modify intrinsic risk factors is greatest in the preseason period, and improvements in aerobic-running fitness and increased body mass may protect against in-season injury in elite Australian football.
Asunto(s)
Traumatismos en Atletas/epidemiología , Índice de Masa Corporal , Fútbol Americano/lesiones , Aptitud Física/fisiología , Medición de Riesgo/métodos , Traumatismos en Atletas/prevención & control , Estudios de Seguimiento , Humanos , Incidencia , Masculino , Estudios Prospectivos , Victoria/epidemiología , Adulto JovenRESUMEN
Whole-body vibration (WBV) has been shown to be effective for increasing lower-body power; however, the combination of frequency, displacement, and duration that elicits the best acute response has yet to be determined. The purpose of this study was to identify the protocol eliciting the greatest improvement in power after an acute bout of WBV. Forty men and women participated in this study, in which 8 different combinations of 30, 35, 40, and 50 Hz with 2-mm and 5-mm displacements were tested over 3 days. For all protocols, randomized to reduce potential order effects, subjects underwent 30 seconds of WBV while holding an isometric squat at a knee angle of 2.27 rad. Power was assessed by countermovement jumps. Subjects performed 3 jumps before WBV, immediately afterward, and 1, 5, and 10 minutes later. The highest normalized peak power (nPP) at each time point was determined using a 4 (frequency) x 2 (displacement) x 5 (time) repeated-measures analysis of variance. Significant effects were seen for frequency (p < or = 0.026) and time (p < or = .0001). Post hoc analyses revealed that the 30-Hz condition (1.010 +/- 0.003) produced a higher nPP than 35 Hz (1.00 +/- 0.003, p < or = 0.026) and 40 Hz (1.002 +/- 0.002, p < or = 0.028) but not 50 Hz (1.004 +/- .002). We also found a significantly higher nPP for the 1-minute post-treatment time point (1.011 +/- .0003) vs. all other time points (p < or = 0.006). Our data show that an acute WBV bout can significantly increase power output at 1 minute post-treatment across all frequencies and displacements, although 30 Hz appears to have a greater effect on power output than either 35 Hz or 40 Hz, but not 50 Hz, at all post-treatment time points.
Asunto(s)
Fuerza Muscular/fisiología , Aptitud Física/fisiología , Vibración/uso terapéutico , Adulto , Ejercicio Físico/fisiología , Femenino , Humanos , MasculinoRESUMEN
Power is an important component of general health, fitness, and athletic performance. Traditional overload techniques require considerable time, intensity, and volume of training. Whole-body vibration (WBV) is a potentially less time-consuming method for increasing power performance than traditional training. However, the exact protocols that can maximize power output have not yet been identified. Eleven healthy men, aged 32.3 +/- 4.1 years, and 9 healthy women, aged 29.1 +/- 3.5 years, performed countermovement jumps (CMJs) of maximal volition to assess peak power pre and post (immediately and at 1, 5, and 10 minutes) randomized WBV stimuli set at different frequency (30, 35, 40, and 50 Hz), displacement (2-4 vs. 4-6 mm), and duration (30, 45, and 60 seconds) combinations. Repeated-measures analysis of variance on peak power normalized to initial power (nPP) revealed no significant effects attributable to duration of stimulus. However, high frequencies were more effective when combined with high displacements, and low frequencies were more effective in conjunction with low displacements (p < 0.05). Additionally, the greatest improvements in nPP occurred at 1 minute posttreatment, with significant improvements lasting through 5 minutes posttreatment (p < 0.05). Optimal acute effects can be attained using as little as 30 seconds of WBV, and they are highest from 1 to 5 minutes posttreatment. Additionally, high frequencies were most effective when applied in conjunction with high displacements, whereas low frequencies were most effective when applied in conjunction with low displacements.