RESUMEN
OBJECTIVE: The purpose of this study was to assess the effect of holding an external load on the standing balance of younger and older adults with and without chronic low back pain (CLBP). METHODS: Twenty participants with and 20 without CLBP participated in the study. Each group contained 10 younger (50% men) and 10 older adults (50% men). Participants were instructed to look straight ahead while standing on a force platform during two 120-second trials with and without holding an external load (10% of body mass). The center of pressure area, mean velocity, and mean frequency in the anteroposterior and mediolateral directions were measured. RESULTS: Older adults had worse standing balance than younger adults did (P < .001, d = 0.20). There were no significant balance differences between participants with and without CLBP within age groups during standing balance condition. However, holding the external load significantly increased postural instability for both age groups and CLBP status, with mean effect size across center of pressure variables of d = 0.82 for older participants without CLBP and d = 2.65 for younger participants without CLBP. These effects for people with CLBP were d = 1.65 for subgroup of older and d = 1.60 for subgroup of younger participants. CONCLUSION: Holding an external load of 10% of body mass increased postural instability of both younger and older adults with and without CLBP.
Asunto(s)
Dolor Crónico/diagnóstico , Dolor de la Región Lumbar/diagnóstico , Equilibrio Postural/fisiología , Postura/fisiología , Soporte de Peso , Adulto , Factores de Edad , Anciano , Envejecimiento/fisiología , Índice de Masa Corporal , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Persona de Mediana Edad , Valores de Referencia , Levantamiento de Peso/fisiologíaRESUMEN
PURPOSE: The purpose of this study was to examine the effects of an additional set of exhaustive exercise before traditional hypertrophic training on quadriceps muscle performance in young men. METHODS: Subjects performed maximal dynamic strength (1RM), local muscular endurance (LME), and magnetic resonance imaging (MRI) tests before and after an 8-week hypertrophic training program using a knee extensor machine. After baseline testing, the subjects were divided into 3 groups: untrained control, traditional training (TR), and prior exhaustive training (PE). Both the TR and PE groups trained using the same training protocol (2 days week(-1); 3 sets of 8-12 repetitions at 75 % of 1RM); the only difference was that the PE group performed an additional set of exhaustive exercise at 20 % of 1RM before each training session. RESULTS: After 8 weeks, the PE group experienced a greater (P < 0.05) increase in 1RM, cross-sectional area, and LME than the TR group. Additionally, no changes (P > 0.05) in daily dietary intake were observed between groups. CONCLUSION: These results suggest that the inclusion of a single set of exhaustive exercise at 20 % of 1RM before traditional hypertrophic training can be a suitable strategy for inducing additional beneficial effects on quadriceps strength, hypertrophy, and endurance in young men.