Lower Body Muscle Groups Research Articles

Effect of Creatine and Protein Supplementation Combined With Resistance Training on Muscle Mass and Strength in Older Men

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Differences in Size, Strength, and Power of Upper and Lower Body Muscle Groups in Young and Older Men

We compared muscle thickness, torque, normalized torque (torque/muscle thickness), and power at 1.05 rad/s and 3.14 rad/s in flexor and extensor muscles of the elbow and knee, and in ankle plantar flexors in young (n=22, 18-31 years) and older (n=28, 59-76 years) men. Young men had greater muscle thickness for all muscle groups (p<.01), except elbow extensors, which were similar to older men. Young men had greater torque and power at both velocities for all muscle groups (p<.01), and greater normalized torque at both velocities for the elbow extensors and knee flexors and at the fast velocity for knee extensors. Relative to young mean values, muscle thickness, and torque, normalized torque, and power in the older group were most affected for lower-body measurements, especially at the fast velocity. Torque, normalized torque, and power (especially at fast velocities), and muscle thickness in the lower body are affected more by aging than are upper body measures in men.

Muscle Activation Is Enhanced With Multi- and Uni-Articular Bilateral Versus Unilateral Contractions

Ten resistance trained (RT) and 6 non-resistance trained (NRT) subjects were used to determine differences in quadriceps activation between isometric single and double knee extensions and squat contractions. Greater inactivation, as measured by the interpolated twitch technique, was recorded with single (RT: 16.5%, NRT: 17.6%) than double leg extensions (RT: 8.4%, NRT: 13.4%) or squats (RT: 4.03%, NRT: 1.7%). There was no significant difference between the maximum voluntary contraction (MVC) force of the dominant leg during single and double leg extensions. However, in NRT subjects, the contralateral or non-dominant leg during double leg extensions exhibited significantly less force than the dominant leg (715.9 vs 566.9 N). This deficit may be due to a lesser reliance on the non-dominant limb. The contractions of multiple lower body muscle groups enhanced the activation of the dominant quadriceps. Greater levels of activation may be necessary to cope with the stabilization necessary for bilateral and multi-articular contractions.

Effects of an omnivorous diet compared with a lactoovovegetarian diet on resistance-training-induced changes in body composition and skeletal muscle in older men

Very limited data suggest that meat consumption by older people may promote skeletal muscle hypertrophy in response to resistance training (RT). The objective of this study was to assess whether the consumption of an omnivorous (meat-containing) diet would influence RT-induced changes in whole-body composition and skeletal muscle size in older men compared with a lactoovovegetarian (LOV) (meat-free) diet. Nineteen men aged 51-69 y participated in the study. During a 12-wk period of RT, 9 men consumed their habitual omnivorous diets, which provided approximately 50% of total dietary protein from meat sources (beef, poultry, pork, and fish) (mixed-diet group). Another 10 men were counseled to self-select an LOV diet (LOV-diet group). Maximal strength of the upper- and lower-body muscle groups that were exercised during RT increased by 10-38% (P < 0.001), independent of diet. The RT-induced changes in whole-body composition and skeletal muscle size differed significantly between the mixed- and LOV-diet groups (time-by-group interactions, P < 0. 05). With RT, whole-body density, fat-free mass, and whole-body muscle mass increased in the mixed diet group but decreased in the LOV- diet group. Type II muscle fiber area of the vastus lateralis muscle increased with RT for all men combined (P < 0.01), and the increase tended to be greater in the mixed-diet group (16.2 +/- 4.4 %) than in the LOV diet group (7.3 +/- 5.1%). Type I fiber area was unchanged with RT in both diet groups. Consumption of a meat-containing diet contributed to greater gains in fat-free mass and skeletal muscle mass with RT in older men than did an LOV diet.

Lack of association of anabolic hormone status and muscle strength with regional and whole body bone mineral density in healthy men aged 60–79 years

This study investigated the capacity of muscle strength and anabolic hormone status to predict regional and whole body bone mineral density (BMD) in older men. Fifty-two healthy men aged 60-79 years served as subjects. BMD of the lumbar spine, proximal femur, upper and lower limbs, and whole body was assessed by dual X-ray absorptiometry. Dynamic muscle strength for several upper and lower body muscle groups was determined by the one-repetition maximum and isometric grip strength by dynamometry. Anabolic hormone status was assessed by the ratio of testosterone (T) to sex hormone binding globulin (SHBG), given as the free androgen index (FAI), and the ratio of insulin-like growth factor I (IGF-I) to IGF binding protein-3 (IGFBP-3). Age was associated with declines in dynamic strength and the log FAI. In stepwise regression analysis, only body mass was an independent predictor of whole body and upper limb BMD (R2 = 0.13), and hip adductor strength predicted the Ward's triangle (R2 = 0.14). For lumbar spine BMD, triceps extensor strength was significantly correlated (r = 0.36, p < 0.01), while no strength or hormonal variable was associated with the femoral neck, trochanter, or lower limb. The lack of association between muscle strength and BMD was generally unaltered after controlling for hormone status and body mass. There was no difference in BMD when analyzed by tertiles of log FAI or IGF-I/IGFBP-3 or by tertiles of muscle strength. These results suggest that in healthy community-dwelling men in the seventh and eighth decade, muscle strength and hormonal status are not significant contributors to regional or whole body BMD.

HABITUAL EXERCISE DOES NOT PREVENT THE AGE-ASSOCIATED DECLINE IN GROWTH HORMONE/INSULIN LIKE GROWTH FACTOR-I 25

Human aging is associated with a decline in secretion of growth hormone and insulin like growth factor-I (GH/IGF-I), which has been proposed to contribute to the observed somatic changes in older people. This decline in GH/IGF-I may be due to aging per se or to a reduction in physical activity that also commonly occurs with age. Acute exercise is known to stimulate GH secretion. To determine if habitual exercise prevents or retards age associated changes in GH/IGF-1 status or body composition and muscle strength, we compared 15 masters runners (Active, A) with 15 sedentary men (Non-Active, NA), aged 60 - 70 yrs. Maximal oxygen uptake (VO2 max) assessed by treadmill testing was higher in A than NA (40.0 ± 1.9 vs. 27.3 ± 1.4 ml/kg/min, mean ± SEM, P < 0.001). There was no difference in lean body mass, regional or whole body bone mineral density, but NA had higher (P < 0.05) body weight (73.8 ± 1.8 vs. 84.8 ± 4.0 kg), fat mass (12.8± 0.8 vs. 20.3 ± 2.2 kg) and percent fat (23.2 vs. 17.2) than A as assessed by DXA (Hologic 1000/W). Total IGF-I (A, 129 ± 10 ng/mL vs. NA, 124 ± 11 ng/mL) and the ratio IGF-1:IGFBP3, an index of bioavailable IGF-1 (A, 0.046 vs. NA, 0.048) were similar between goups. Concentric muscle strength (1-RM) for 8 upper and lower body muscle groups was comparable except for knee extension, where A were higher than NA (P < 0.05). With groups combined, there was no relationship between total or bioavailable IGF-I and any body composition or muscle strength variable. Conclusions: These results indicate that even high levels of endurance exercise do not prevent the decline in GH/IGF-I that occurs with normal human aging, and that neither total or bioavailable IGF-I predicts somatic status or muscle strength in healthy older men.

Physical performance and physiological responses following 60 hours of sleep deprivation

The effect of 60 h of sleep deprivation (SD) upon physical performance and physiological responses to exercise was examined in 11 male subjects. The experiment consisted of two conditions separated by at least 10 d. In the experimental condition (E) subjects remained awake for 60 h and in the control condition (C) the same subjects had 7 h of sleep per night. In both conditions subjects reported to the laboratory on the evening prior to d 1 and slept for 7 h. Physical performance testing was carried out on d 1 and again on d 3 after either two nights of sleep or two nights of SD. Results obtained on d 3 are expressed relative to d 1, the control day. Maximal isometric and isokinetic muscular strength and endurance of selected upper and lower body muscle groups, performance of the Wingate Anaerobic Power Test, simple reaction time, the blood lactate response to cycle exercise at 70% VO2max, and most of the cardiovascular and respiratory responses to treadmill running at 70% and 80% VO2max, were not significantly altered as a result of SD. These results suggest that sleep loss of up to 60 h will not impair the capability for physical work, a finding of considerable importance in sustained military operations which frequently involve the combination of both physical and mental tasks.

Reproductive hormone responses to resistance exercise

To investigate if changes in circulating testosterone levels during isokinetic resistance exercise in women were similar to those during intense aerobic exercise and to examine concomitant changes in hemoconcentration, specific binding protein (sex hormone binding globulin-binding capacity), non-sex hormone binding globulin bound testosterone, luteinizing hormone, follicle-stimulating hormone, cortisol, and lactate, blood samples were obtained through an indwelling cannula at 30 and 15 min before exercise, after each of six exercises on upper and lower body muscle groups, and at 15 and 30 min after exercise in seven normal menstruating women. Investigations lasting approximately 60 min were performed in the early follicular phase beginning at 3.30 p.m. after two months of training with isokinetic ("Nautilus") equipment. Baseline testosterone and non-sex hormone binding globulin bound testosterone levels were significantly higher in subjects than in a control group. Increased total and non-sex hormone binding globulin bound testosterone was observed immediately prior to exercise with further increases late in exercise, then with proportional increases in cortisol and lactic acid. Sex hormone binding globulin-binding capacity increased before exercise. The testosterone increments exceeded hemoconcentration. Luteinizing hormone and follicle-stimulating hormone levels increased during exercise. The data suggest that origins of the exercise-associated testosterone increment are complex, resulting from hemoconcentration and specific gonadal and adrenal responses.