Improved Muscle Strength and Power in Elderly ...

G. C. Gauchard1,2 A. Tessier3 C. Jeandel4 Ph. P. Perrin1,2,5

Improved Muscle Strength and Power in Elderly Exercising Regularly

Since the number of elderly people with a sedentary lifestyle is considerable and still growing, regular exercise could be an extra stimulant to compensate for the decrease in functional capacities. The potential positive effects of physical and sporting activities (PSA) on muscular function in relation to the period of practice were studied. Muscular strength and power were evaluated by dynamometric knee and ankle tests on 40 healthy subjects aged over 60 years old, split into four groups according to the period of practice. Higher muscular performance was obtained in subjects who had always practised PSA, whereas subjects who had always been inactive displayed the worst muscular performances. Subjects who had begun PSA practice lately had good

muscular strength and power, close to those of the AA group, whereas the subjects who had stopped the practice at an early age did not perform as well. Life-long PSA attenuates the agerelated loss of muscle function, and initiation at old age improves it. This, and the absence of any beneficial effects of PSA stopped when young, indicates that the actual activity level is an important determinant of skeletal muscle function at old age. Practicing PSA increases muscular strength and power and thus improves daily living activities in elderly people.

Training & Testing

Abstract

Key words Muscular strength and power · elderly · physical and sporting activities · period of activity

71 Introduction Balance control is a complex process involving sensory contribution provided by visual, vestibular and somatosensory information, central integration in the vestibular nuclei located in the brainstem, and motor response. Among the components of these different levels of postural regulation, ageing leads to a structural modification of muscular effectors, especially by a reduction of muscular mass [22], which can reach 50 % between the second and the eighth decade [28]. This muscular atrophy seems to be due to a reduction in the size of muscular fibres [22], mainly of

1

type 2 (fast-twitch fibres) [17, 27], replaced by fat and connective tissue [22]. Muscular fibres may also decrease in number although the literature provides conflicting evidence on this issue [22]. Moreover, motor units are modified with age, with decreased numbers [10] and an increase of their innervation ratio [26]. All these age-related muscular modifications lead to a reduction in muscular strength [5, 29] of about 10 % to 15 % per decade [6], and in power [7]. This muscular alteration leads to functional ability alterations, i. e. slower gait [3] or poorer balance control [11]. Postural muscle appears to be affected more than

Affiliation Unit/ de Formation et de Recherche en Sciences et Techniques des Activit/s Physiques et Sportives (UFR STAPS), Universit/ Henri Poincar/-Nancy 1, Villers-l7s-Nancy, France 2 National Institute for Health and Medical Research (INSERM), U 420, Facult/ de M/decine, Vandoeuvre-l7s-Nancy, France 3 Office d’Hygi7ne Sociale, Centre Jacques Parisot, Bainville-sur-Madon, France 4 Centre de G/rontologie, Clinique Antonin-Balm7s, Montpellier, France 5 Laboratoire d’Exploration Fonctionnelle, Service ORL, Centre Hospitalier Universitaire de Nancy, Vandoeuvre-l7s-Nancy, France

Correspondence Prof. Ph. Perrin, M.D., Ph. D. · Equilibration et Performance Motrice · Unit/ de Formation et de Recherche en Sciences et Techniques des Activit/s Physiques et Sportives (UFR STAPS) · Universit/ Henri Poincar/-Nancy 1 · 30, rue du Jardin Botanique · 54600 Villers-l7s-Nancy · France · Phone: + 33 383 682 929 · Fax: + 33 383 154 647 · E-Mail: [email protected] Accepted after revision: June 15, 2002 Bibliography Int J Sports Med 2003; 24: 71–74 H Georg Thieme Verlag Stuttgart · New York · ISSN 0172-4622

non-postural muscle [14]. Moreover, muscular strength is strongly influenced by inactivity [16, 25].

Training & Testing

The practice of physical and sporting activities (PSA) is now known to increase muscular strength [1, 2,15] and several authors have demonstrated a relationship between this improvement in strength and the quality of postural control in the elderly [9,16, 23, 30]. Aniansson & Gustafsson [2] observed that a 12week strength-training program in elderly men increased the strength of lower limb muscles. Agre et al. [1] also found in elderly women an improvement in muscular strength following a 25-week light resistance and aerobic program. Frontera et al. [15] showed that a 12-week resistance training programme in the elderly led to an increase in leg extensor muscular strength and type II fibre area. Lord & Castell [23] through a program of walking, flexibility and strength exercises demonstrated improved muscular strength, reaction time and body sway on firm and soft surfaces. Wolfson et al. [30] have shown that balance training and Tai Chi can improve balance, but that strength training does not modify postural regulation. All these studies concern training program setting-up, and few provide information on the long-term benefits of practicing sport regularly [16, 24]. The aim of this study was to examine the effects of long-term and regular practice of PSA on muscular strength and power in the elderly, and to determine whether it is beneficial for an elderly person to start regular physical activity at an advanced age when motivation to begin exercising is not certain.

Materials and Methods

72

Subjects Forty subjects (28 women and 12 men) aged over 60 (72.6 N 6.7 years old) were recruited from a cohort of elderly subjects taking part in a larger study on age-related physiology. They were free from any pathology of the central nervous system and did not show any orthopaedic disorder either of the trunk or of the lower limbs. All lived at home and could perform daily tasks without help. They were all submitted to muscular function tests and also underwent bone densitometry, an ear, nose and throat examination, and psychometric and balance evaluation. All the subjects had comparable body mass indexes and none was or had been a professional sportsperson. This study was accepted by the local ethical committee and every subject had given his or her informed consent prior to the study. Each subject completed a questionnaire and took part in a complementary interview [24] concerning the practice or absence of PSA, the period in the subject’s life when the PSA was practised (age of subject and duration of practice), and the frequency (number of times per week) and intensity (number of hours per session). Spare time activities such as do-it-yourself were considered as a physical activity. All these data allowed the subjects to be split into four groups according the period of PSA practice: – The first group, comprising 7 subjects (4 women, 3 men, mean age 70.6 N 8.7 years) who had practised PSA all their life (more than 40 years) with only a minor interruption if any, was

called “active-active“ (AA). They still practised at least one PSA regularly, principally swimming, cycling, jogging, soft gymnastics and do-it-yourself. Jogging (n = 2) was practised twice a week for one hour at least per session, swimming (n = 4) once or twice a week for one hour at least per session, and cycling (n = 2) for about 25 km per week. Soft gymnastics (n = 3) were practised once or twice a week in 90 min sessions. – The second group comprising 15 people (10 women, 5 men, mean age 70.7 N 5.4 years) who began practicing PSA after retiring at least 4 years previously, was considered “inactive-active” (IA). Jogging (n = 6), swimming (n = 5), cycling (n = 4) and soft gymnastics (n = 4) were practised at the same frequency and intensity as group AA. Three men only did do-it-yourself regularly. All subjects of groups AA and IA also walked once a week for about 5 km as part of the same club for the elderly. – The third group comprising 7 people (6 women, 1 man, mean age 75.1 N 6.2 years), who had practised PSA during their youth and definitively stopped at least 30 years ago, was described as “active-inactive” (AI). None had been forced to stop owing to vertigo or serious trauma. – The fourth group comprising 11 subjects (8 women, 3 men, mean age 74.9 N 7.0 years) who had never practised PSA was called “inactive-inactive” (II). Muscular function test: evaluation of muscular strength and power Muscular tests were performed on an isokinetic dynamometer (Biodex Corp., Shirley, NY) to determine the muscular strength and power in both legs, for the knee and ankle extensors and flexors. In this type of exercise, the speed is controlled whilst resistance is variable according to the amount of force throughout the range of movement. The motion of the body segment is kept at a predetermined slow angular velocity of 908 per second for the knee and of 608 per second for the ankle [16]. For the dynamometric knee tests, the subject was positioned on the examination chair with a hip flexion angle of approximately 1158, stabilized with self-adhesive straps around the thigh tested as well as around the abdomen and thorax, to prevent any movement liable to affect the measurements. The axis of the knee tested was aligned with the rotation axis of the dynamometer, itself in line with the lateral femoral condyle. For the dynamometric ankle tests, the subject sat on the examination chair with the thigh raised to form a 608 angle at hip level, and the foot placed on a platform allowing a knee flexion of 908. The pelvis was strapped to the chair. The axis of the ankle joint was aligned with the rotational axis of the dynamometer. A preliminary warm-up on an ergocycle was performed to prepare the muscles of the subjects for the effort. This consisted of pedalling for 15 minutes without resistance to avoid fatigue. Five successive flexion-extension movements were performed without a rest period and with verbal stimulation to encourage the subjects to do the movement as quickly and strongly as possible. The best result for each muscle tested was taken into account (Fig. 1).

Gauchard GC et al. Muscle and Sport in Elderly People … Int J Sports Med 2003; 24: 71 – 74

Training & Testing

Fig. 1 Muscular function tests performed for the knee (graph a) and ankle (graph b) extensors and flexors. Unbroken line in graph a represents 5 successive movements of extension (higher curve part) and flexion (lower curve part); unbroken line in graph b represents 5 successive movements of flexion (lower curve part) and extension (higher curve part), providing maximal muscular strength (Newton-meters) and power (Newton-meters per second). Dotted line (Graphs a and b) represents the angular velocity (degree per second).

Statistics Statistics were performed with the Statview Software using ANOVA. Statistical significance was considered for p values lower than 0.05.

Results Fig. 2 shows the muscular strength (a) and power (b) results obtained for knee extension and flexion, and ankle extension and flexion in the four groups. Whatever the level and movement studied, group AA subjects displayed the best strength and power results, whereas group II subjects displayed the worst. Group IA values were close to those observed in group AA, whereas those of group AI were close to those observed in group II. Statistically significant differences were observed for the main parameters between the active and inactive groups, but never between the two active groups or the two inactive groups.

Fig. 2 Mean results, topped by SD, of muscular strength (graph a) and power (graph b) in group AA (white bars), IA (light grey bars), AI (dark grey bars) and II (black bars), for knee extension strength and power (KES, KEP), knee flexion strength and power (KFS, KFP), ankle extension strength and power (AES, AEP), and ankle flexion strength and power (AFS, AFP) as obtained in the dynamometric isocinetismtest. Results are expressed in Newton-meters (Nm; graph a), or Newton-meters per second (Nm/s; graph b). Statistical significance is indicated as follows: *p < 0.05, **p < 0.01, ***p < 0.001.

Discussion This study has shown that, in elderly people, regular practice of PSA on a continual basis throughout life (group AA) significantly preserves muscular function, and that inactivity (group II) is an unfavourable factor. Moreover, it seems that a recent period of PSA practice (group IA) could favourably contribute to muscular strength and power improvement, and that practising a PSA when young but having definitively stopped (group AI) generates no experience, and the performance is close to those of inactivity. The muscles must be able generate adequate external force rapidly enough to ensure physical performance. Certain everyday tasks such as rising from a chair, walking up stairs, and locomotion, require good muscular strength and power, particularly at knee extensor muscle level [4,16]. Moreover, the muscular strength and power of the ankle plantar flexors and dorsiflexors play an important role in the regulation of balance control [18], and gait velocity [20]. A weakness at this level is highly correlated with poor balance, an increased risk of falling [29], and a reduction in gait velocity [20]. The quality of motor response is highly implicated in balance regulation [31] and is partly depen-

dent on muscular status; an increase in muscular strength and power can therefore lead to an improvement in postural control [16]. Moreover, several studies have shown that carefully selected training programs for the elderly increase muscular strength [1, 2,15,16] and are correlated with an improvement in functional capacities [13, 23]. Muscle adaptations to training concern the increase in muscular mass and fibre area, and improved oxidative capacity and capillary density [21]. Our results confirm the benefits induced by exercise showing that lower limbs muscular strength and power are higher in elderly people who performed sustained regular exercise, whereas inactivity is correlated with lower muscular values. The latter is consistent with other studies which have demonstrated that a settled way of life, which does not activate any mechanisms to counteract the effects of aging, especially on the muscles, is responsible for muscular deterioration and thus a decrease in strength and power [19, 25]. Moreover, this study indicates that starting PSA during old age is beneficial for the muscles and restores muscle strength and power levels to near those acquired by lifelong regular practice. Skeletal muscle is known to be a very plastic and adaptable tissue,


73

Training & Testing 74

and training can compensate for the age-related changes in function and morphology of the aging human skeletal muscle [13]. Several studies have shown that the best type of training to increase muscular strength is resistance training, whereas endurance training seems to have a lower impact [8,12,15]. In these different studies, the reported increases in strength with strength training varied from a few percent [1, 8] to over 200 % [12,15], whereas endurance training produced a improvement in strength of less than 20 % [8]. In the present study, the main activities practised were more of the endurance or aerobic type, and the strength and power increase induced, around 40 %, was higher than in the literature. This result could be explained by the duration of training; in our case, PSA practice is not a shortterm training program lasting only a few weeks, but a long-term one of about 4 years. This increase in strength by sustained training could lead to a significant improvement in daily living activities. Finally, this study shows that the muscular strength and power gained by practising PSA during youth but then definitively stopping does not carry through to later life, the values being similar to those obtained in the absence of sporting activities throughout life. This result is confirmed by a study based on detrained effects [12]. When subjects resumed their sedentary life-style after training ended, a muscular test after only 4 weeks of detraining indicated a significant decrease in quadriceps strength [12]. Improvement in muscular strength is not maintained in the absence of continued training. In conclusion, a decrease in muscular strength and power is common in elderly people and provokes disorders in several daily living activities. Skeletal muscle being a plastic and adaptable tissue, even in the elderly, the practice of physical and sporting activities can counteract the effect of ageing on muscular function. This study confirms that inactivity is a worsening factor of ageing, and also suggests that physical and sporting activities, such as jogging, cycling or other bioenergetic activities, once or twice a week for one hour at least, without cardiovascular contraindication, have to be recommended to elderly people even if they have never practised earlier in their life.

References 1

Agre JC, Pierce LE, Raab DM, McAdams M, Smith EL. Light resistance and stretching exercise in elderly women: Effect upon strength. Arch Phys Med Rehabil 1988; 69: 273 – 276 2 Aniansson A, Gustafsson E. Physical training in elderly man with special reference to quadriceps muscle and morphology. Clin Physiol 1981; 7: 87 – 98 3 Bassey EJ, Bendall MJ, Pearson M. Muscle strength in the triceps surae and objectively measured customary walking activity in men and women over 65 years of age. Clin Sci 1988; 74: 85 – 89 4 Bassey EJ, Fiatarone MA, O’Neill EF, Kelley M, Evans WJ, Lipsitz LA. Leg extensor power and functional performance in very old men and women. Clin Sci 1992; 82: 321 – 327 5 Bemben MG, Massey BH, Bemben DA, Misner JE, Boileau RA. Isometric force production as a function of age in healthy 20- to 74-yr-old men. Med Sci Sports Exerc 1991; 23: 1302 – 1310 6 Bonnefoy M, Kostka T, Arsac LM, Berthouze S, Lacour JM. Different determinants of peak anaerobic power in elderly men. Eur J Appl Physiol 1998; 77: 182 – 188

7

Brooks SV, Faulkner JA. Maximum and sustained power of extensor digitorium longus muscles from young, adult and old mice. J Gerontol 1991; 46: B28 – 33 8 Buchner DM, Cress ME, de Lateur BJ, Wagner EH. Variability in the effect of strength training on skeletal muscle strength in older adults. In: Albarede JL, Garry PJ, Vellas P (eds). L’Ann/e G/rontologique; Volume 7 Paris:Serdi Publishers 1993: 229 – 239 9 Campbell AJ, Robertson MC, Gardner MM, Norton RN, Tilyard MW, Buchner DM. Randomised control trial of a general practice programme of home-based exercise to prevent falls in elderly women. Br Med J 1997; 315: 1065 – 1069 10 Doherty TJ, Brown WF. The estimated numbers and relative sizes of thenar motor units as selected by multiple point stimulation in young and older adults. Muscle Nerve 1993; 16: 355 – 366 11 Era P, Heikkinen E. Postural sway during standing and unexpected disturbance of balance in random samples of men of different ages. J Gerontol 1985; 40: 287 – 295 12 Fiatarone MA, Marks EC, Ryan ND, Meredith CN, Lipsitz LA, Evans WJ. High-intensity strength training in nonagenarians. JAMA 1990; 263: 3029 – 3034 13 Fiatarone MA, O’Neill EF, Ryan ND, Clements KM, Solares GR, Nelson ME, Roberts SB, Kehayias JJ, Lipsitz LA, Evans WJ. Exercise training and nutritional supplementation for physical frailty in very elderly people. New Engl J Med 1994; 330: 1769 – 1775 14 Fitts RH, Troup JP, Witzman FA, Holloszy JO. The effect of aging and exercise on skeletal muscle function. Mech Ageing Dev 1984; 27: 161 – 172 15 Frontera WR, Meredith CN, O’Reilly KP, Knuttgen HG, Evans WJ. Strength conditioning in older men: Skeletal muscle hypertrophy and improved function. J Appl Physiol 1988; 64: 1038 – 1044 16 Gauchard GC, Jeandel C, Tessier A, Perrin PhP. Beneficial effect of proprioceptive physical activities on balance control in elderly human subjects. Neurosci Lett 1999; 273: 81 – 84 17 Grimby G, Aniansson A, Zetterberg C, Saltin B. Is there a change in relative muscle fiber composition with age? Clin Physiol 1984; 4: 189 – 194 18 Horak FB, Nashner LM. Central programming of postural movements: adaptation to altered support-surface configurations. J Neurophysiol 1986; 55: 1369 – 1381 19 Hurley BF. Age, gender, and muscular strength. J Gerontol 1995; 50A (sp issue): 41 – 44 20 Judge JO, Davis RB 3rd, Ounpuu S. Step length reductions in advanced age: the role of ankle and hip kinetics. J Gerontol 1996; 51: M303 – 312 21 Kirkendall DT, Garrett WE. The effects of aging and training on skeletal muscle. Am J Sports Med 1998; 26: 598 – 602 22 Lexell J. Human aging, muscle mass, and fiber type composition. J Gerontol 1995; 50A (sp issue): 11 – 16 23 Lord SR, Castell S. Physical activity program for older persons: effects on balance, strength, neuromuscular control, and reaction time. Arch Phys Med Rehabil 1994; 75: 648 – 652 24 Perrin PhP, Gauchard GC, Perrot C, Jeandel C. Effects of physical and sporting activities on balance control in elderly people. Br J Sports Med 1999; 33: 121 – 126 25 Sandler RB, Burdett R, Zaleskiewicz M, Sprowls-Repcheck C, Harwell M. Muscle strength as an indicator of physical activity. Med Sci Sports Exerc 1991; 23: 1375 – 1381 26 Stalberg E, Borges O, Ericsson M, Esses-Gustavsson B, Fawcett PRW, Nordesjo LLO, Nordgren B, Uhlin R. The quadriceps femoris muscle in 20–70-year-old subjects: Relationship between knee extension torque, electrophysiological parameters, and muscle fiber characteristics. Muscle Nerve 1989; 12: 382 – 389 27 Tomonaga M. Histochemical and ultrastructural changes in senile human skeletal muscle. J Am Geriatr Soc 1977; 25: 125 – 131 28 Tzankoff SP, Norris AH. Longitudinal changes in basal metabolic rate in man. J Appl Physiol 1978; 33: 536 – 539 29 Whipple RH, Wolfson LI, Amerman PM. The relationship of knee and ankle weakness to falls in nursing home residents: An isokinetic study. J Am Geriatr Soc 1987; 35: 13 – 20 30 Wolfson L, Whipple R, Derby C, Judge J, King M, Amerman P, Schmidt J, Smyers D. Balance and strength training in older adults: intervention gains and Tai Chi maintenance. J Am Geriatr Soc 1996; 44: 498 – 506 31 Woollacott MH. Systems contributing to balance disorders in older adults. J Gerontol 2000; 55A : M424 – 428
