Increased muscular challenge in older adults during obstructed gait

Department of Human Physiology, University of Oregon, Eugene, Oregon, United States
Gait & Posture (Impact Factor: 2.75). 01/2006; 22(4):356-61. DOI: 10.1016/j.gaitpost.2004.11.012
Source: PubMed


Skeletal muscle strength is known to decline with age. Although lower extremity (LE) muscle strength is critical to maintaining dynamic stability, few studies have investigated lower extremity muscle challenge during activities of daily living. The purpose of this study was to investigate the effects of age and obstructed gait on relative lower extremity muscular challenge, with respect to available joint strength. Fifteen healthy young and fifteen healthy older adults were asked to walk over level ground and step over obstacles. Pre-amplified surface electrodes were used to measure bilateral muscular activation of the gluteus medius (GM), vastus lateralis (VL), and gastrocnemius (GA). Muscle activation signals were normalized to peak magnitudes collected during maximal manual muscle testing (MMT). Normalized magnitudes were analyzed during the double-support phase for gluteus medius and vastus lateralis and during the single-support phase for gastrocnemius. A two-factor ANOVA was used to test for age group effect, with repeated measure of obstacle height. In general, older adults demonstrated greater relative activation levels compared to young adults. Gluteus medius activity was significantly greater in the elderly as compared to young during periods of double-support (weight transfer). Increased obstacle height resulted in greater relative activation in all muscles, confirming the increased challenge to the musculo-skeletal system. While healthy elderly adults were able to successfully negotiate obstacles of different heights during walking, their muscular strength capacity was significantly lower than young adults, resulting in relatively higher muscular demands. The resulting potential for muscular fatigue during locomotion may place individuals at higher risk for trips and/or falls.

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Available from: Michael E Hahn
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    • "According to our results regarding the EMG measurements , higher obstacles induced minimal, nonsignificant increase in the EMG amplitude of the calf muscles during stance or swing phase. In a previous study, comparing the EMG of elderly and young people during obstacle crossing it was observed that increased obstacle height induces higher muscle activation (Hahn et al., 2005). Nonetheless, for the young population, this increase was marginal and probably not significant, which is in accordance with our findings. "
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    ABSTRACT: The aim of this study was to investigate the effect of fatigue on electromyographic (EMG) parameters of healthy young adults during obstacle crossing of two different heights. Twelve un-trained male adults (23 ± 5 years of age) were fatigued running on a treadmill with increasing speed and inclination and walked over an obstacle with a height set at 10% and 20% of each indi-vidual's lower limb length. Maximal plantar flexor torque and EMG of the medial gastrocnemius, soleus, and tibialis anterior muscles of the trailing limb were assessed during obstacle cross-ing. Data were captured before, immediately after and 5 minutes after a fatigue session. Fatigue induced significant reduction on the plantar flexor torque output immediately after and 5 minutes after exhaustion. After fatigue gait speed was not affected, the minimum distance between the obstacle and the trailing or leading foot remained unchanged, and the trailing foot contacted the ground closer to the obstacle immediately after fatigue. Regarding the EMG, medial gastrocnemius became after fatigue more active during swing phase when increasing the obstacle height, whereas this was not the case before or 5 minutes after fatigue. No other significant difference was observed for any of the examined muscles. It is concluded that the assessed fatigue protocol induced only minimal changes in the EMG activity of the examined muscles during obstacle crossing. Therefore, it is suggested that the neuromuscular system of healthy young individuals is able to respond to the decreased force capacity after fatigue during obstacle crossing of heights up to the 20% of the limb length.
    Full-text · Article · Dec 2014 · Journal of sports science & medicine
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    • "traffic lights and noises) or internal (e.g. apprehension and fear) factors (Beauchet et al., 2005; Hahn et al., 2005). Several studies showed that older adults have reduced walking speed and increased kinematic parameters variability than younger adults during dual task gait (Brach et al., 2010; Perry et al., 2010; Taylor et al., 2013). "

    Full-text · Article · Jun 2013 · Journal of Electromyography and Kinesiology
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    • "Falls are a major concern in health care for older adults because most falls are associated with a high risk of fractures, resulting in a need for long-term care [1-3]. The etiology of falls is multifactorial and among them a most important problem leading to falls [4-7] would be a tripping when stepping over an obstacle. However, previous studies have primarily focused on age-related decline in physical ability or muscular strength [1,3,8-10] and visuomotor control of foot movements [11-14] as predominant factors in tripping during the step-over action. "
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    ABSTRACT: Background Older adults could not safely step over an obstacle unless they correctly estimated their physical ability to be capable of a successful step over action. Thus, incorrect estimation (overestimation) of ability to step over an obstacle could result in severe accident such as falls in older adults. We investigated whether older adults tended to overestimate step-over ability compared with young adults and whether such overestimation in stepping over obstacles was associated with falls. Methods Three groups of adults, young-old (age, 60–74 years; n, 343), old-old (age, >74 years; n, 151), and young (age, 18–35 years; n, 71), performed our original step-over test (SOT). In the SOT, participants observed a horizontal bar at a 7-m distance and estimated the maximum height (EH) that they could step over. After estimation, they performed real SOT trials to measure the actual maximum height (AH). We also identified participants who had experienced falls in the 1 year period before the study. Results Thirty-nine young-old adults (11.4%) and 49 old-old adults (32.5%) failed to step over the bar at EH (overestimation), whereas all young adults succeeded (underestimation). There was a significant negative correlation between actual performance (AH) and self-estimation error (difference between EH and AH) in the older adults, indicating that older adults with lower AH (SOT ability) tended to overestimate actual ability (EH > AH) and vice versa. Furthermore, the percentage of participants who overestimated SOT ability in the fallers (28%) was almost double larger than that in the non-fallers (16%), with the fallers showing significantly lower SOT ability than the non-fallers. Conclusions Older adults appear unaware of age-related physical decline and tended to overestimate step-over ability. Both age-related decline in step-over ability, and more importantly, overestimation or decreased underestimation of this ability may raise potential risk of falls.
    Full-text · Article · May 2013 · BMC Geriatrics
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