Jamie S. McPhee

Eccentric exercise as an adjuvant to influenza vaccination in humans.

The immune response to vaccination in animals can be enhanced by exposure to acute stress at the time of vaccination. The efficacy of this adjuvant strategy for vaccination in humans requires investigation. The current study employed a randomised controlled trial design to examine the effects of eccentric exercise prior to influenza vaccination on the antibody and cell-mediated responses. Sixty young healthy adults (29 men, 31 women) performed eccentric contractions of the deltoid and biceps brachii muscles of the non-dominant arm (exercise group) or rested quietly (control group), and were vaccinated 6h later in the non-dominant arm. Change in arm circumference and pain were measured to assess the physiological response to exercise. Antibody titres were measured pre-vaccination and at 6- and 20-week follow-ups. Interferon-gamma in response to in vitro stimulation by the whole vaccine, an index of the cell-mediated response, was measured 8 weeks post-vaccination. Interferon-gamma responses were enhanced by exercise in men, whereas antibody titres were enhanced by eccentric exercise in women but not in men. Men showed greater increase in arm circumference after eccentric exercise than women but there was no difference in reported pain. The interferon-gamma response was positively associated with the percentage increase in arm circumference among the exercise group. Eccentric exercise exerted differential effects on the response to vaccination in men and women, with enhancement of the antibody response in women, but enhancement of the cell-mediated response in men. Eccentric exercise of the muscle at the site of vaccine administration should be explored further as a possible behavioural adjuvant to vaccination.

Age-dependent alteration in muscle regeneration: the critical role of tissue niche

Although adult skeletal muscle is composed of fully differentiated fibers, it retains the capacity to regenerate in response to injury and to modify its contractile and metabolic properties in response to changing demands. The major role in the growth, remodeling and regeneration is played by satellite cells, a quiescent population of myogenic precursor cells that reside between the basal lamina and plasmalemma and that are rapidly activated in response to appropriate stimuli. However, in pathologic conditions or during aging, the complete regenerative program can be precluded by fibrotic tissue formation and resulting in functional impairment of the skeletal muscle. Our study, along with other studies, demonstrated that although the regenerative program can also be impaired by the limited proliferative capacity of satellite cells, this limit is not reached during normal aging, and it is more likely that the restricted muscle repair program in aging is presumably due to missing signals that usually render the damaged muscle a permissive environment for regenerative activity.

Physical activity in older age: perspectives for healthy ageing and frailty

Regular physical activity helps to improve physical and mental functions as well as reverse some effects of chronic disease to keep older people mobile and independent. Despite the highly publicised benefits of physical activity, the overwhelming majority of older people in the United Kingdom do not meet the minimum physical activity levels needed to maintain health. The sedentary lifestyles that predominate in older age results in premature onset of ill health, disease and frailty. Local authorities have a responsibility to promote physical activity amongst older people, but knowing how to stimulate regular activity at the population-level is challenging. The physiological rationale for physical activity, risks of adverse events, societal and psychological factors are discussed with a view to inform public health initiatives for the relatively healthy older person as well as those with physical frailty. The evidence shows that regular physical activity is safe for healthy and for frail older people and the risks of developing major cardiovascular and metabolic diseases, obesity, falls, cognitive impairments, osteoporosis and muscular weakness are decreased by regularly completing activities ranging from low intensity walking through to more vigorous sports and resistance exercises. Yet, participation in physical activities remains low amongst older adults, particularly those living in less affluent areas. Older people may be encouraged to increase their activities if influenced by clinicians, family or friends, keeping costs low and enjoyment high, facilitating group-based activities and raising self-efficacy for exercise.

Upper Limb Muscle-Bone Asymmetries and Bone Adaptation in Elite Youth Tennis Players.

INTRODUCTION The study of tennis players allows the nonracket arm to act as an internal control for the exercising racket arm. In addition, the study of the upper limbs removes the influence of gravitational loading, allowing the examination of the influence of muscular force on bone adaptation. METHODS The role of muscular action on bone, strength parameters of the radius, ulna (both at 4% and 60% distal-proximal ulnar length), and humerus (at 35% distal-proximal humerus length) as well as muscle size in both arms of 50 elite junior tennis players (mean ± SD age = 13.5 ± 1.9 yr) were measured with peripheral quantitative computed tomography (pQCT). RESULTS Strong relationships were found between muscle size and bone size in both arms (all correlations, P < 0.001, R = 0.73-0.86). However, the muscle-bone ratio was significantly lower (P < 0.001) in the upper arm on the racket side (compared with the contralateral arm). In addition, material eccentricity analysis revealed that bone strength in bending and torsion increased more than strength in compression as the moment arms for these actions (bone length and width, respectively) increased (in all cases, P > 0.001, R = 0.06-0.7) with relationships being stronger in torsion than in bending. Large side differences were found in bone strength parameters and muscle size in all investigated sites, with differences in distal radius total BMC (+37% ± 21%) and humerus cortical cross-sectional area (+40% ± 12%) being most pronounced (both P < 0.001). CONCLUSIONS These results support a strong influence of muscular action on bone adaptation; however, interarm muscle-bone asymmetries suggest factors other than local muscle size that determine bone strength. The results also suggest that torsional loads provide the greatest stress experienced by the bone during a tennis stroke.

Age‐related neuromuscular changes affecting human vastus lateralis

Skeletal muscle size and strength decline in older age. The vastus lateralis, a large thigh muscle, undergoes extensive neuromuscular remodelling in healthy ageing, as characterized by a loss of motor neurons, enlargement of surviving motor units and instability of neuromuscular junction transmission. The loss of motor axons and changes to motor unit potential transmission precede a clinically‐relevant loss of muscle mass and function.

Exercise as an intervention for first‐episode psychosis: a feasibility study

Exercise can improve psychiatric symptoms, neurocognitive functioning and physical health in schizophrenia. However, the effects in early psychosis have not been explored. This study aimed to assess the feasibility of an exercise intervention for early psychosis and to determine if it was associated with changes in physical and mental health.

Manual segmentation of individual muscles of the quadriceps femoris using MRI: A reappraisal

To propose a manual segmentation method for individual quadriceps femoris (QF) muscles and to test its reliability for muscle volume estimation.

The training stimulus experienced by the leg muscles during cycling in humans

Considerable variability exists between people in their health‐ and performance‐related adaptations to conventional endurance training. We hypothesized that some of this variability might be due to differences in the training stimulus received by the working muscles. In 71 young sedentary women we observed large variations in the ratio of one‐leg cycling muscle aerobic capacity to two‐leg cycling whole‐body maximal oxygen uptake ( ; Ratio1:2; range 0.58–0.96). The variability in Ratio1:2 was primarily due to differences between people in one‐leg (r= 0.71, P < 0.0005) and was not related to two‐leg (r= 0.15, P= 0.209). Magnetic resonance imaging (n= 30) and muscle biopsy sampling (n= 20) revealed that one‐leg was mainly determined by muscle volume (r= 0.73, P < 0.0005) rather than muscle fibre type or oxidative capacity. A high one‐leg was associated with favourable lipoprotein profiles (P= 0.033, n= 24) but this was not the case for two‐leg . Calculations based on these data suggest that conventional two‐leg exercise at 70% requires subjects with the lowest Ratio1:2 to work their legs at 60% of single‐leg , whilst those with the highest Ratio1:2 work their legs at only 36% of maximum. It was concluded that endurance training carried out according to current guidelines will result in highly variable training stimuli for the leg muscles and variable magnitudes of adaptation. These conclusions have implications for the prescription of exercise to improve health and for investigations into the genetic basis of muscle adaptations.

A robust neuromuscular system protects rat and human skeletal muscle from sarcopenia

Declining muscle mass and function is one of the main drivers of loss of independence in the elderly. Sarcopenia is associated with numerous cellular and endocrine perturbations, and it remains challenging to identify those changes that play a causal role and could serve as targets for therapeutic intervention. In this study, we uncovered a remarkable differential susceptibility of certain muscles to age-related decline. Aging rats specifically lose muscle mass and function in the hindlimbs, but not in the forelimbs. By performing a comprehensive comparative analysis of these muscles, we demonstrate that regional susceptibility to sarcopenia is dependent on neuromuscular junction fragmentation, loss of motoneuron innervation, and reduced excitability. Remarkably, muscle loss in elderly humans also differs in vastus lateralis and tibialis anterior muscles in direct relation to neuromuscular dysfunction. By comparing gene expression in susceptible and non-susceptible muscles, we identified a specific transcriptomic signature of neuromuscular impairment. Importantly, differential molecular profiling of the associated peripheral nerves revealed fundamental changes in cholesterol biosynthetic pathways. Altogether our results provide compelling evidence that susceptibility to sarcopenia is tightly linked to neuromuscular decline in rats and humans, and identify dysregulation of sterol metabolism in the peripheral nervous system as an early event in this process.

The Impact of Different Diagnostic Criteria on the Prevalence of Sarcopenia in Healthy Elderly Participants and Geriatric Outpatients

Background: A consensus on the diagnostic criteria for sarcopenia, a common syndrome in the elderly, has not been reached yet. Prevalence rates vary between studies due to the use of different criteria encompassing different measures, correction factors and cutoff points. Objective: This study compared prevalence rates of sarcopenia using nine sets of diagnostic criteria applied in two different elderly populations. Methods: The study population encompassed 308 healthy elderly participants (152 males, 156 females; mean age 74 years) and 123 geriatric outpatients (54 males, 69 females; mean age 81 years). Diagnostic criteria included relative muscle mass, absolute muscle mass, muscle strength and physical performance. Results: Prevalence rates of sarcopenia varied between 0 and 15% in healthy elderly participants and between 2 and 34% in geriatric outpatients. Conclusion: This study clearly demonstrates the dependency of sarcopenia prevalence rates on the applied diagnostic criteria.