Motor unit survival in lifelong runners is muscle dependent.
نویسندگان
چکیده
UNLABELLED A contributing factor to the loss of muscle mass and strength with adult aging is the reduction in the number of functioning motor units (MUs). Recently, we reported that lifelong competitive runners (master runners = ~66 yr) had greater numbers of MUs in a leg muscle (tibialis anterior) than age-matched recreationally active controls. This suggested that long-term exposure to high levels of physical activity may limit the loss of MU numbers with adult aging. However, it is unknown if this finding is the result of long-term activation of the specifically exercised motoneuron pool (i.e., tibialis anterior) or an overall systemic neuroprotective effect of high levels of physical activity. PURPOSE The purpose was to estimate the number of functioning MUs (MUNEs) in the biceps brachii (an upper body muscle not directly loaded by running) of nine young (27 ± 5 yr) and nine old (70 ± 5 yr) men and nine lifelong competitive master runners (67 ± 4 yr). METHODS Decomposition-enhanced spike-triggered averaging was used to measure surface and intramuscular EMG signals during elbow flexion at 10% of maximum voluntary isometric contraction. RESULTS Derived MUNEs were lower in the biceps brachii of runners (185 ± 69 MUs) and old men (133 ± 69 MUs) than the young (354 ± 113 MUs), but the old and master runners were similar. CONCLUSIONS Although there were no significant differences in MUNE between both older groups in the biceps brachii muscle, with the number of subjects tested here, we cannot eliminate the possibility of some whole-body neuroprotective effect. However, when compared with the remote biceps muscle, a greater influence on age-related spinal motoneuron survival was found in a chronically activated MN pool specific to the exercised muscle.
منابع مشابه
Motor unit number estimates in masters runners: use it or lose it?
INTRODUCTION A contributing factor to the loss of muscle mass and strength during aging is the reduction in the number of functioning motor units (MU). It has been shown that lifelong physically active older rats have greater numbers of MU compared with age-matched sedentary controls, suggesting that chronic exercise may preserve MU function with advancing age. This has not previously been exam...
متن کاملMotor unit number estimates and neuromuscular transmission in the tibialis anterior of master athletes: evidence that athletic older people are not spared from age‐related motor unit remodeling
Muscle motor unit numbers decrease markedly in old age, while remaining motor units are enlarged and can have reduced neuromuscular junction transmission stability. However, it is possible that regular intense physical activity throughout life can attenuate this remodeling. The aim of this study was to compare the number, size, and neuromuscular junction transmission stability of tibialis anter...
متن کاملExercise-associated Muscle Cramps in Runners: A Review
Objective: Exercise-associated Muscle Cramp (EAMC) is an intense, painful, and involuntary contraction of skeletal muscles during a physical activity. Runners are more prone to this syndrome than other athletes. The present paper aims to review of the literature on EAMC in runners to determine the reasons and nature of EAMC in this sports field. Methods: A search was conducted for related stud...
متن کاملUse it or Lose It: Tonic Activity of Slow Motoneurons Promotes Their Survival and Preferentially Increases Slow Fiber-Type Groupings in Muscles of Old Lifelong Recreational Sportsmen
Histochemistry, immuno-histochemistry, gel electrophoresis of single muscle fibers and electromyography of aging muscles and nerves suggest that: i) denervation contributes to muscle atrophy, ii) impaired mobility accelerates the process, and iii) lifelong running protects against loss of motor units. Recent corroborating results on the muscle effects of Functional Electrical Stimulation (FES) ...
متن کاملSpinal Muscular Atrophy: A Short Review Article
Spinal muscular atrophy (SMA) is a genetic disorder which affect nervous system and is characterized with progressive distal motor neuron weakness. The survival motor neuron (SMN) protein level reduces in patients with SMA. Two different genes code survival motor neuron protein in human genome. Skeletal and intercostal muscles denervation lead to weakness, hypotony, hyporeflexia, respiratory fa...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Medicine and science in sports and exercise
دوره 44 7 شماره
صفحات -
تاریخ انتشار 2012