RESUMEN
Although muscle power is an important factor affecting independence in older adults, there is no inexpensive or convenient test to quantify power in this population. Therefore, this pilot study examined whether regression equations for evaluating muscle power in older adults could be derived from a simple chair-rise test. We collected data from a 30-second chair-rise test performed by fourteen older adults (76 +/- 7.19 years). Average (AP) and peak (PP) power values were computed using data from force-platform and high-speed motion analyses. Using each participant's body mass and the number of chair rises performed during the first 20 seconds of the 30-second trial, we developed multivariate linear regression equations to predict AP and PP. The values computed using these equations showed a significant linear correlation with the values derived from our force-platform and high-speed motion analyses (AP: R = 0.89; PP: R = 0.90; P < 0.01). Our results indicate that lower-body muscle power in fit older adults can be accurately evaluated using the data from the initial 20 seconds of a simple 30-second chair-rise test, which requires no special equipment, preparation, or setting.
Asunto(s)
Actividades Cotidianas , Evaluación de la Discapacidad , Modelos Biológicos , Actividad Motora/fisiología , Fuerza Muscular/fisiología , Anciano , Anciano de 80 o más Años , Fenómenos Biomecánicos , Femenino , Humanos , Pierna/fisiología , Modelos Lineales , Masculino , Proyectos Piloto , Valor Predictivo de las PruebasRESUMEN
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.
Asunto(s)
Rendimiento Atlético/fisiología , Resistencia Física/fisiología , Recuperación de la Función/fisiología , Deportes/fisiología , Vibración , Adulto , Prueba de Esfuerzo/métodos , Femenino , Humanos , Masculino , Contracción Muscular/fisiología , Fatiga Muscular/fisiología , Educación y Entrenamiento Físico/métodos , Aptitud Física , Probabilidad , Factores de Tiempo , Adulto JovenRESUMEN
CONTEXT: There are numerous ways to overload the scapular stabilizers. OBJECTIVES: To assess scapular stabilizer activity using the Bodyblade and other traditional training devices. DESIGN: Repeated measures analysis of surface EMG data collected from the upper trapezius (UT), lower trapezius (LT), and serratus anterior (SA) during shoulder flexion and abduction using Bodyblade, cuff weight, and Thera-Band resistance. SETTING: Laboratory. PARTICIPANTS: Thirty collegiate athletes (20.0 +/- 1.7 years). INTERVENTION: Participants performed 10 repetitions of shoulder flexion and abduction. MAIN OUTCOME MEASURES: For each movement, normalized root mean square values (NrmsEMG) were computed for each muscle during each repetition under each training condition. Data were analyzed using 3 (condition) 3 10 (repetition) repeated measures ANOVAs. RESULTS: During shoulder flexion and abduction, the NrmsEMG of the UT, LT, and SA were significantly greater when using the Bodyblade than the Thera-Band or cuff weight. CONCLUSION: The Bodyblade produces greater scapular activity than traditional resistance techniques.
Asunto(s)
Movimiento/fisiología , Músculo Esquelético/fisiología , Escápula/fisiología , Articulación del Hombro/fisiología , Medicina Deportiva/instrumentación , Adulto , Electromiografía , Femenino , Humanos , Contracción Isométrica/fisiología , Masculino , Soporte de Peso/fisiologíaRESUMEN
This study investigated variations in electromyographic (EMG) responses of the erector spinae (ES), vastus medialis (VM), rectus femoris (RF), and vastus lateralis (VL) to different seatback angles during leg extension. Twenty men and women (10 men, 10 women; age 27.49 +/- 6.16 years) performed 8 repetitions at 70% of 8 repetition maximum at seatback angles of 1.57, 1.75, and 1.92 radius (rad). Analyses using repeated-measures analysis of variance indicated the greatest root square mean of the EMG (rmsEMG) and integrated EMG (intEMG) for the ES were at 1.92 rad, and the greatest for the VM (concentric) and VL (eccentric) were at 1.57 rad. No differences were observed among seat angles for the RF except for a higher normalized intEMG at 1.92 than 1.75 rad (concentric). Throughout all sets for all conditions and muscles, rmsEMG and intEMG significantly increased and median power frequency significantly decreased. These data indicate that a seatback angle of 1.57 rad is best for a leg extension machine, because this angle maximizes quadriceps activity while minimizing stress on the lower back muscles.