EFFECT OF HIGH INTENSITY TRAINING AND ISOINERTIAL TRAINING ON MUSCLE FUNCTIONS IN OLDER ADULTS

Introduction Maximal muscle strength is a strong predictor of functional skills and ability to maintain independent living in elderly. Muscle\r\ncontraction properties has been shown to decline to a greater extent than muscle strength with aging and it has been considered the\r\nmain responsible of the observed decline in functional status (Izquierdo et al., 1999). Endurance high intensity interval training (HIT), by\r\ninvolving large muscle groups, and eccentric strength exercise (IRT), by producing high mechanical loads, could be used in elderly to\r\nimprove muscle function and quality of life (Milanovi et al., 2015). Therefore, the aim of this study was to examine the changes in muscle\r\nproperties in elderly after 8 wk of HIT and IRT. Methods 12 moderately active older adults (age: 69.4±4.3 yy; BMI: 22.9±2.7 kg/m2;\r\nV’O2max: 29.5±4.1 mL/kg/min) have completed 8 wk of: i) HIT, 7 two-minute cycling repetitions at 90% of V’O2max, 3 times/wk, and,\r\nafter 4 months, ii) IRT performed with an isoinertial leg press (YoYo TechnologyAB) comprised 4×7 maximal concentric-eccentric knee\r\nextensions, 3 times/wk. Maximum voluntary contraction (MVC) was measured using a cell load in a custom-made setup (90° knee\r\nflexion). Electrically evoked muscle single twitch was superimposed onto MVC: neuromuscular activation (NA) was calculated as the ratio\r\nbetween the amplitudes of the superimposed and resting twitches. Muscle volume of the quadriceps (Qvol) was obtained by MRI scans.\r\nResults MVC at 90° knee flexion, increase significantly only after IRT (P < 0.01). Both training modalities affected significantly NA (P < 0.05):\r\n+12.4% after HIT and +14.2 after IRT. Similarly, Qvol increase by 5.1% (P < 0.05) after HIT intervention and by 4.9% (P < 0.05) after IRT.\r\nDiscussion Our results confirm the feasibility and effectiveness of HIT and IRT to improve muscle qualities: 8 wk of specific training are\r\nable to modify muscle mass, MVC and neuromuscular activation in elderly subjects. This stresses the importance of using effective approaches\r\nsuch as exercise treatment with high loads and high intensities in the prevention of disuse in elderly individuals who are concurrently\r\nexposed to the deleterious effects of aging on muscle contractile function and mass (Behrens et al., 2016). We can therefore\r\nspeculate that the two proposed training modalities may be helpful in improving functional status and prevent frailty in elderly subjects.\r\nReferences Izquierdo M, Aguado X, Gonzalez R, Lopez JL, Hakkinen K. (1999). Eur J Appl Physiol Occup Physiol, 79, 260-7. Milanovi Z,\r\nSporiš G, Weston M. (2015). Sports Med, 45(10), 1469-81. Behrens M, Brown N, Bollinger R, Bubeck D, Mau-Moeller A, Weippert M, Zschorlich\r\nV, Bruhn S, Alt W. (2016). Appl Physiol Nutr Metab, 41(1), 110-3.