Linda S. Lamont

Menstrual cycle and exercise effects on protein catabolism.

The purpose of this investigation was to determine whether exercise at different times of the menstrual cycle alters protein catabolism. Nine women exercised for 60 min at 70% VO2max when serum estradiol (E) and progesterone (P) were low (menses) and when both were high [mid-luteal (ML)]. Diet was reproduced on both occasions. Serum urea nitrogen (N), E, and P were analyzed at rest, after 15, 30, 45, and 60 min of exercise, and 15 min into recovery. Sweat urea N excretion was also determined. Urinary area N excretion was measured the day before, the day of, and 2 d following exercise. E and P were significantly greater in the ML phase, and this difference was maintained throughout exercise (P less than 0.05). No change was seen in serum urea N across exercise or between phases. Both exercise day urinary urea N excretion and total urea N excretion in sweat and urine, when added across all experimental days, were significantly greater in the ML phase compared to menses (8.5 +/- 0.96 vs 5.5 +/- 0.81 g and 24.8 +/- 2.38 vs 19.3 +/- 1.38 g, respectively, P less than 0.05). The data suggest that the greater protein use in the ML phase was due to the combined effects of exercise, a changing hormonal milieu and other unknown causes.

Relationship between leucine oxidation and oxygen consumption during steady-state exercise.

PURPOSE The purpose of this study was to assess the relationship between whole-body leucine oxidation and oxygen consumption during steady-state exercise. Our hypothesis was that leucine oxidation will be responsive to increased whole-body energy needs. METHODS Sixteen healthy individuals (7 women and 9 men) were infused with a stable isotope of leucine and, for comparison purposes, lysine during 60 min of moderate-intensity exercise. RESULTS Leucine oxidation was increased (P < 0.05) and nonoxidative leucine disposal was decreased (P < 0.05), whereas leucine and lysine rate of appearance remained unchanged (P = NS) during exercise. Linear regression analysis indicated a modest relationship between leucine oxidation and steady-state oxygen consumption (R = 0.69; P < 0.003) during steady-state exercise. The coefficient of determination (R(2) = 0.49) indicates that approximately half of the variance in whole-body leucine oxidation during exercise can be explained by whole-body oxygen consumption. CONCLUSION In a statistically appropriate sample size of humans whose dietary intake was controlled, the whole-body rate of leucine oxidation during exercise was only partially influenced by energy demands.

Exercise Training Alters Skeletal Muscle Mitochondrial Morphometry in Heart Failure Patients

Background Previous research has demonstrated that exercise intolerance in heart failure patients is associated with significant alterations in skeletal muscle ultrastructure and oxidative metabolism that may be more consequential than cardiac output. Design To examine the effect of exercise training on skeletal muscle mitochondrial size in chronic heart failure patients. Methods Six heart failure patients participated in 16-weeks of supervised upper and lower extremity exercise training. At the conclusion of training, percutaneous needle biopsies of the vastus lateralis were taken and electron microscopy was used to assess mitochondrial sizes. Results The exercise programme resulted in a significant increase in peak maximal oxygen consumption (P < 0.05) and anaerobic threshold (P < 0.04). Knee extension muscle force increased following training (P < 0.02). After exercise training, the average size of the mitochondria increased by 23.4% (0.036 to 0.046 m2, P < 0.015) and the average shape was unaltered. Conclusion Exercise training with heart failure patients alters skeletal muscle morphology by increasing mitochondrial size, with no change in shape. This may enhance oxidative metabolism resulting in an increased exercise tolerance.

β1-adrenoreceptors regulate resting metabolic rate

This was a randomized, cross-over experiment designed to determine which beta-adrenergic receptors, beta 1, beta 2, or both, regulate metabolic rate in humans. All subjects (3 women, 4 men) were administered a 7-d therapeutic dose of a selective beta 1-antagonist (atenolol 50 mg BID), a combined beta 1, beta 2-antagonist (propranolol 80 mg BID), and a placebo control (BID). Indirect calorimetry was determined before and after 1 h of submaximal exercise. Exercise was performed at 50% of the trial specific VO2peak because maximal exercise was significantly decreased in the presence of the nonselective beta 1, beta 2-antagonist (VO2peak placebo: 44.90 +/- 4.40 mL.kg-1.min-1 vs beta 1, beta 2-antagonism: 39.20 +/- 3.00 mL.kg-1.min-1; P < 0.05). Both the beta 1 and the combined beta 1, beta 2-adrenoreceptor antagonists reduced resting oxygen consumption to a similar extent (0.247 +/- 0.007 L.min-1 placebo, vs 0.218 +/- 0.007 L.min-1 beta 1-antagonism, vs 0.226 +/- 0.007 L.min-1 beta 1, beta 2-antagonism; P < 0.05). However, the 30-min and 60-min excess post-exercise oxygen consumption (mean EPOC) remained unchanged. It is concluded that the beta 1-receptors are regulating the effects of the sympathetic nervous system on resting but not exercise recovery metabolic rate. These metabolic side effects may suggest that changes need to be made in the nutritional requirements of patients using beta-adrenergic antagonists.

Fat-free mass and gender influences the rapid-phase excess postexercise oxygen consumption

The purpose of this study was to determine the influence of gender dimorphism and body composition on postexercise oxygen consumption during the rapid recovery phase. We compared the rapid-phase excess postexercise oxygen consumption (EPOC) in men and women matched for age (32.1 years), physical activity status, and maximal oxygen consumption (44.7 mL*kg(-1)*min(-1)), but not for body mass or fat-free mass (FFM). All subjects exercised for 1 h at 50% of their peak capacity. Although there were differences between genders in the magnitude of the absolute oxygen consumption and EPOC during the rapid phase of recovery, there were no differences found when EPOC was corrected for FFM. We conclude that the gender differences in the absolute O(2) consumption and EPOC are related to the size of the FFM.

Postmenopausal effects of resistance training on muscle damage and mitochondria.

Abstract Manfredi, TG, Monteiro, MA, Lamont, LS, Singh, MF, Foldvari, M, White, S, Cosmas, AC, and Urso, ML. Postmenopausal effects of resistance training on muscle damage and mitochondria. J Strength Cond Res 27(2): 556–561, 2013—The purpose of this study was to measure the effects of a 12-month progressive resistance training intervention on muscle morphology and strength gains in postmenopausal women. Skeletal muscle biopsies were obtained from the vastus lateralis of 5 independent community-dwelling women (mean age: 75.6 ± 4.28 years; mean height: 163 ± 5.34 cm; mean weight: 72 ± 17.5 kg) before 6 months and 12 months after progressive resistance training. Muscle strength (1 repetition maximum) was measured at the same time points. After 6 months of training, morphological analysis revealed evidence of increased proteolysis and tissue repair, and rudimentary fiber development. The percent of Z-bands with mild Z-band disruption increased from 43.9% at baseline to 66.7% after 6 months of training (p < 0.01). Mitochondrial volume also increased (percent of mitochondria = 0.86% at baseline, 1.19% at 6 months, and 1.04% at 12 months, p < 0.05), and there was a shift to larger sized mitochondria. The training did not result in statistically significant increases in muscle leg strength (p < 0.18). It appears that mild Z-band disruption acts as a precursor for increased protein synthesis and stimulates an increase in mitochondrial mass. Therefore, although a progressive resistance training program in this population did not increase muscle strength, it did demonstrate clinical applications that lend support to the importance of resistance training in older adults.

The ocean as a unique therapeutic environment: developing a surfing program.

Educational aquatic programming offers necessary physical activity opportunities to children with disabilities and the benefits of aquatic activities are more pronounced for children with disabilities than for their able-bodied peers. Similar benefits could potentially be derived from surfing in the ocean. This article describes an adapted surfing program that was designed to develop and enhance the childrens strength, flexibility, range of motion, coordination, balance, and psychosocial development. Throughout the program, the children and their surf instructors were encouraged to set realistic individual goals. Many positive outcomes were derived from the project, including gains in social development and self-confidence.

Benefits of Surfing for Children with Disabilities: A Pilot Study

The purpose of this study was to assess the effectiveness of an eight-week surfing intervention for 16 children with disabilities. The assessment procedure consisted of pre and post physical fitness measures to determine the benefits of this intervention. Our results showed an overall improvement in upper body strength (right: P = 0.024, left: P = 0.022), core strength (P = 0.002) and cardiorespiratory endurance (P = 0.013). This research is the first of its kind, illustrating the feasibility and effectiveness of a surfing intervention on improving the physical fitness of children with disabilities.

A simple ergometer modification can expand the exercise options for wheelchair clients

Purpose. Wheelchair users are by necessity, limited to upper body exercise and have fewer exercise options. An ergometer found in many homes and fitness facilities can be simply adapted for use by those with lower extremity disabilities. This article outlines a novel modification using polyvinyl chloride(PVC) tubing to an existing exercise ergometer. Method. This adapted device was metabolically tested using 9 paraplegics and 8 healthy controls (mean age of 29 years; mean body mass index BMI of 23.5 kg/m2) and found to allow for the attainment of peak exercise by both groups. Results. The mean peak oxygen consumption was VO2peak = 22 ml/kg/min (6.3 METS). The mean maximal power output was 103 W and the peak heart rate averaged 157 beats per min. Conclusions. A simple modification to a fitness ergometer (dual action exercise bicycle) can allow for its use by the wheelchair mobile client. The potential impact of this work is that it can expand the exercise options for the wheelchair client who is at risk for many lifestyle-induced chronic diseases.

402 ADRENERGIC BLOCKADE HEIGHTENS THE EXERCISE INDUCED INCREASE IN LEUCINE OXIDATION

The purpose of this study was to assess the interaction between beta-blockade and exercise on amino acid kinetics. This was a three-way crossover experiment using beta 1-blockade, beta 1,beta 2-blockade, and a placebo control. Three 6-h L-[1-13C]leucine and L-[alpha-15N]lysine infusions were performed. The first 3 h established an isotopic steady state, and 1 h of exercise (approximately 50% of maximal O2 consumption) and 2 h of recovery followed. Plasma glucose decreased with exercise during all trials (P < 0.0001). During beta 1- and beta 1,beta 2-blockade, plasma free fatty acids were reduced during rest and exercise (P < 0.001). Leucine and lysine rates of appearance were unaffected by beta-blockade during rest but were decreased with placebo exercise. Leucine oxidation increased with beta-blockade (P < 0.01) and exercise (P < 0.001). There was a statistical interaction between both treatments (P < 0.004). In conclusion, leucine oxidation increased with exercise, further increased with beta 1-blockade, and was additionally heightened with beta 1,beta 2-blockade. This cumulative response indicates that leucine oxidation was regulated through beta 1- and beta 2-receptors.