Effects of Lower Extremity Eccentric-Based Training on Muscle Strength and Physical Function in Older Adults: A Randomized Controlled Pilot Trial

Abstract

INTRODUCTIONSkeletal muscle function is the most important element of a healthy and active life in older adults and is closely related to every kind of physical effort [1]. Despite the natural phenomenon of losing muscle mass and strength in the aging process, this has recently been recognized as a disease and has been defined as sarcopenia [2]. The reason for this is that muscle atrophy due to aging is part of several functional disorders, including decreased muscle strength and flexibility, vulnerability to injury, and delayed functional recovery [3][4][5]. Compared to young and middleaged adults, people aged 70-85 years old experience a 30% decrease in muscle mass [6].Resistance training has become a strategy to prevent muscle atrophy [7].It also improves physical function, muscle strength, and the ability to maintain muscle mass [8]. Recently, mechanism-based (power training, eccentric training, high intensity interval training, hybrid electrical stimulation training) interventions incorporated with age-related changes have been attempted in exercise interventions for older adults [9-12]. The age- ORIGINAL ARTICLE PURPOSE:Reduced muscular strength is a key player in loss of physical function and quality of life in older adults. It has been reported that eccentric training has positive effects on the preservation of eccentric strength, produces less delayed onset muscle soreness, and has a lower metabolic cost for older individuals. Therefore, the present study investigated the effects of eccentric-based training on skeletal muscle strength and physical function in older adults. METHODS:Sixteen healthy older subjects (over the age of 65) participated either in eccentric training group (ETG, n=8) or in conventional resistance training group (CTG, n=8) twice a week for eight weeks. The ETG group performed motorized eccentric training, and the CTG group performed a leg press using air pressure. Physical function and muscular strength assessments were performed before and after 8 weeks. The primary outcomes for physical function included gait speed, stair climbing, and the chair stand test, and the secondary outcomes included muscle strength and power. RESULTS:The ETG group demonstrated significant improvements in physical function (gait speed and stair climbing) and muscle strength (isokinetic strength and power in knee tests) (p<.05) compared to the CTG group after 8 weeks. There were no significant differences for chair stand test (p>.05) after 8 weeks. CONCLUSIONS:Motorized eccentric-based training was more effective in improving muscle strength and physical function in aged individuals than conventional resistance training, which s suggests that eccentric training is may be more beneficial for older individuals to improve overall physical function.

Applications of Eccentric Exercise to Improve Muscle and Mobility Function in Older Adults

“…These results indicated that pure eccentric exercise using specialized equipment might improve overall muscle strength to a greater extent than eccentrically-biased or combined eccentric and concentric contraction 31 , 42 ) and that this treatment modality can overload the muscular system at a low energy cost. 43 ) Therefore, eccentric exercise can produce relatively high intensity with low volume, making it an attractive exercise option in strength programs to improve physical performance in older adults.…”

“…Isokinetic strength and power were also significantly increased following training using an eccentric ergometer. 31 ) However, LaStayo et al 32 ) reported no significant differences between traditional resistance and eccentric groups in the fall risk variables of mobility and leg extensor muscle power. However, as this study did not employ power training in the eccentric or conventional resistance exercise, it would be hard to expect significant changes in variables related to power output.…”

“…Some studies 31 - 35 ) used specialized equipment, such as eccentric ergometers, isokinetic dynamometers, and flywheel ergometers. Kim et al, 31 ) Mueller et al, 33 ) and LaStayo et al 32 ) used eccentric ergometers for eccentric training. Mueller et al 33 ) reported a significant increase in isometric strength.…”

Potential Benefits of a Minimal Dose Eccentric Resistance Training Paradigm to Combat Sarcopenia and Age-Related Muscle and Physical Function Deficits in Older Adults

“…Exercise session durations for multi-joint eccentric training have varied considerably within the broad (all adult ages) literature from a more minimal dose (e.g., three/min sessions) ( Gordon et al, 2019 ; Crane et al, 2020 ) up to 30 min/sessions ( Dibble et al, 2006 ; Suh et al, 2017 ; Lim and Lee, 2018 ; Kim et al, 2019 ). While a three/min exercise session may represent a minimal training approach, this previous work was conducted in young adults ( Gordon et al, 2019 ; Crane et al, 2020 ).…”

“…Commonly investigated training frequencies in eccentric training studies vary from two ( Johnson et al, 2018 , 2019 ; Kim et al, 2019 ; Kay et al, 2020 ; Kumar, 2021 ) and three exercise sessions per week ( Dibble et al, 2006 ; Jacobs et al, 2014 ; Tanner et al, 2015 ; Lim and Lee, 2018 ; Reidy et al, 2018 ), with ( Byrne et al, 2016 ) reporting that, “a frequency of twice weekly can produce significant improvements in power and physical function. A compelling case for lower training session frequency is that a “less is more” exercise session frequency was found to be much more preferred among older adults ( Foley et al, 2011 ).…”