BackgroundStretching exercises are able to promote adaptations in the muscle-tendon unit
(MTU), which can be tested through physiological and biomechanical variables.
Identifying the key variables in MTU adaptations is crucial to improvements in
training.ObjectiveTo perform an exploratory factor analysis (EFA) involving the variables often used
to evaluate the response of the MTU to stretching exercises.MethodMaximum joint range of motion (ROMMAX), ROM at first sensation of
stretching (FSTROM), peak torque (torqueMAX), passive
stiffness, normalized stiffness, passive energy, and normalized energy were
investigated in 36 participants during passive knee extension on an isokinetic
dynamometer. Stiffness and energy values were normalized by the muscle
cross-sectional area and their passive mode assured by monitoring the EMG
activity.ResultsEFA revealed two major factors that explained 89.68% of the total variance: 53.13%
was explained by the variables torqueMAX, passive stiffness, normalized
stiffness, passive energy, and normalized energy, whereas the remaining 36.55% was
explained by the variables ROMMAX and FSTROM.ConclusionThis result supports the literature wherein two main hypotheses (mechanical and
sensory theories) have been suggested to describe the adaptations of the MTU to
stretching exercises. Contrary to some studies, in the present investigation
torqueMAX was significantly correlated with the variables of the
mechanical theory rather than those of the sensory theory. Therefore, a new
approach was proposed to explain the behavior of the torqueMAX during
stretching exercises.
It is still unclear what is the optimum local vibration stimulus (LV) configuration to generate a greater range of motion gain (ROM) and how LV affects the mechanical and sensory responses of the skeletal muscles. This study aimed to compare the acute effects of four LV configurations on mechanical and sensorial variables related to the muscle‐tendon unit response to stretching. Ten male volunteers were randomly undertaken to four LV configurations (LV1: 14 Hz and 3 mm, LV2: 24 Hz and 3 mm, LV3: 14 Hz and 6 mm, and LV4: 24 Hz and 6 mm) at the right hamstrings muscles, and one non‐vibration condition (control). Maximum ROM (ROMMAX) and torque (TORMAX), and their respective values at the first sensation of tightness (FSTROM and FSTTOR) during stretching maneuvers were measured with an isokinetic dynamometer. Passive stiffness (PS) was calculated as the slope of torque vs. angle time‐series. Repeated measures ANOVA revealed differences between the post‐test and pre‐test values (delta) for the ROMMAX and FSTROM between each local vibration condition compared with the control group (P < .05), with no differences among them (P > .05). The four LV configurations were equally able to improve the ROMMAX and FSTROM, being the LV4 the one that produced higher ROMMAX in 40% of the participants.
Concomitantemente à crescente popularidade do Mountain Bike (MTB), houve aumento correspondente de lesões e dores musculoesqueléticas relacionadas à modalidade. Este estudo avaliou os fatores associados à presença de lesões e dores e/ou dormência musculoesquelética (DORMs) em praticantes de MTB. O estudo foi do tipo descritivo e utilizou o questionário Nórdico Musculoesquelético para quantificar as lesões e as DORMs. Foi aplicado o teste de Qui-quadrado, ou teste exato de Fisher, para comparar proporções, e realizada regressão logística binária multivariada para verificar os previsores de lesões e DORMs. Dos 243 participantes avaliados (199 – 81,9% homens), 28 (11,52%) relataram lesões (6 – 13,64% mulheres e 22 – 11,06% homens) e 175 (72,02%) DORMs (33 – 75% mulheres e 142 – 71,36% homens). Os locais mais indicados de DORMs foram as regiões de punhos/mãos (115 – 47,33%), joelhos (44 – 18,11%) e lombar (43 – 17,70%). De acordo com a regressão logística o sobrepeso/obesidade foi preditivo para a presença de DORMs (OR=1,974, IC 95% = 1,105 – 3,526). Os dados analisados mostram que a presença de DORMs é maior do que lesões e o sobrepeso/obesidade está associado com as DORMs, indicando que este fator deve ser considerado no planejamento das atividades para evitar lesões relacionadas ao MTB.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.