Overall muscle strength of extremities is often characterized by measurements from one or more selected actions. This study evaluated the legitimacy of that procedure. Measurements obtained by handheld dynamometry from 13 muscle actions of 156 apparently healthy individuals (50–79 years) were subjected to correlational analysis, principal-components analysis, and cluster analysis. The isometric strengths of all muscle actions correlated significantly with one another (r = .506–.965). Principal-components analysis without rotation showed that all tested actions loaded highly on overall limb muscle strength. Principal-componcnis analysis with varimax rotation revealed high loadings that were grouped by extremity (upper vs. lower). Ankle dorsiflexion strengths were exceptions. These findings, in conjunction with the cluster analysis, support using one or more actions to characterize isometric limb muscle strength among the elderly but suggest that muscle strength in an upper or lower extremity is best characterized by an action (e.g., elbow flexion) of that extremity.
Richard W. Bohannon and A. Williams Andrews
Karen L. Perell, Robert J. Gregor, and A.M. Erika Scremin
The purpose of this study was to determine the effect of bicycle exercise on knee-muscle strength and gait speed in 8 male participants with cerebrovascular accident (CVA). Isokinetic knee-extensor and -flexor strength were measured in both concentric- and eccentric-contraction modes. Fifty-foot walking tests were used for gait speed. After only 4 weeks of stationary recumbent cycling (12 sessions), participants improved eccentric muscle strength of the knee extensors, bilaterally. Walking-speed improvements approached but did not achieve significance with training. Improvement in concentric muscle strength of the knee extensors was observed in the involved limb, although most participants demonstrated a nonsignificant increase in muscle strength in the contralateral limb, as well. No improvements were demonstrated in the knee-flexor muscles. Thus, bicycle exercise serves to improve knee-extensor strength. In addition, these strength improvements might have implications for better control of walking in terms of bilateral improvement of eccentric muscle strength.
Darryn S. Willoughby and Stephen C. Pelsue
This study was an attempt to determine the effects of 12 weeks of moderate-intensity (MIEX) and high-intensity (HIEX) weight training on the muscular strength and qualitative myosin heavy chain (MHO isoform mRNA expression in 18 elderly men. Subjects were randomly assigned to either a control group (Con) or training groups of either MIEX or HIEX. Training sessions occurred 3 days/week and involved three sets of 15-20 repetitions at 60%-65% 1 -RM for MIEX and three sets of 8-10 repetitions at 75%-80% 1 -RM for HIEX. Both upper and lower body strength increased for Con and increased significantly for MIEX and HIEX. No changes in MHC mRNA isoform expression were observed for Con: however, there were increases in Type I MHC and decreases in Type IIx MHC mRNA expression for MIEX and increases in Type I, Ila, and IIx MHC mRNA expression for HIEX. The findings suggest that both moderate- and high-intensity weight training increases muscle strength and the expression of Type I MHC mRNA isoform. while high-intensity weight training also increases the mRNA expression of Type Ila and IIx isoforms in previously inactive elderly men.
Jefferson Fagundes Loss, Edgar Santiago Wagner Neto, Tatiane Borsoi de Siqueira, Aline Dill Winck, Laura Silveira de Moura, and Luiz Carlos Gertz
Trunk-flexor muscle strength plays a fundamental role in athletic performance, 1 – 3 health of children and adolescents, 4 , 5 posture, and rehabilitation. It is also vital for core stability 6 , 7 and situations such as urinary incontinence and athletes’ rehabilitation. 8 Therefore, accurate
Sijie Tan, Jianxiong Wang, and Shanshan Liu
The purpose of this study was to establish the one-repetition maximum (1RM) prediction equations of a biceps curl, bench press, and squat from the submaximal skeletal muscle strength of 4–10RM or 11–15RM in older adults. The first group of 109 participants aged 60–75 years was recruited to measure their 1RM, 4–10RM, and 11–15RM of the three exercises. The 1RM prediction equations were developed by multiple regression analyses. A second group of participants with similar physical characteristics to the first group was used to evaluate the equations. The actual measured 1RM of the second group correlated significantly to the predicted 1RM obtained from the equations (r values were from .633–.985), and standard error of estimate ranged from 1.08–5.88. Therefore, the equations can be used to predict 1RM from submaximal skeletal muscle strength accurately for older adults.
Banu Unver, Kartal Selici, Eda Akbas, and Emin Ulas Erdem
various mechanisms, such as impaired foot posture, decreased muscle strength and range of motion (ROM), and changes in gait parameters. 5 , 6 Therefore, the obese population has much foot pain, functional limitations, and a risk of falls. 4 , 7 – 9 One of the disruptive changes caused by obesity
Maintaining high levels of lower limb muscle strength/size is important to prevent and delay the onset of disability, physical frailty, and dependency. 1 – 3 It is generally accepted that the loss of skeletal muscle strength and size with increased age, sarcopenia, is greater in the lower limbs
Ufuk Ersoy, Umut Ziya Kocak, Ezgi Unuvar, and Bayram Unver
joint structures might contribute to muscle strength. The capability of a joint to alter muscle function is mediated by the articular receptors, and this is called the arthrokinetic reflex (AKR) mechanism. In AKR, 4 types of joint receptors work reciprocally and create reflexogenic effects on muscle
Matthew D. DeLang, Mehdi Rouissi, Nicola L. Bragazzi, Karim Chamari, and Paul A. Salamh
increased bone mass 4 and muscle strength 5 , 6 on the dominant arm may exemplify the training effect on adolescent, growing bodies. Similar adaptations existing in professional players 7 , 8 may not only represent the chronicity of preceding practice to reach that performance but may also provide the
Hitoshi Koda, Yoshihiro Kai, Shin Murata, Hironori Osugi, Kunihiko Anami, Takahiko Fukumoto, and Hidetaka Imagita
movement in which the roles of the lower limbs alternate; when one leg is used for forward progression, the opposite leg is used for support. Therefore, evaluating muscle strength asymmetry rather than limb dominance may be important for assessing walking stability. Laroche et al. ( 2012 ) studied 24