THE AGING FOOT AND ANKLE: A COMPARISON OF YOUNG AND SENIOR ATHLETES

Abstract

Purpose: Previous gait studies in community ambulatory older adults show reduced walking velocity, shorter steps, ankle stiffness, and increased duration of double-limb support. A description of gait in very active older adults is needed.

Methods: Subjects: 13 senior athletes (age 65±4 years) and 13 young athletes (age 24±3 years). Inclusion criteria: running plus other activity, body mass index < 26, no systemic disease, no lower leg pathology. Outcome measures: Subjects were evaluated barefoot (walking 1.5 m/s) using a force platform, motion analysis (frontal, medial and plantar videography), and electromyography (EMG) of tibialis anterior (ta), peroneus longus (pl), gastrocnemius (gc), soleus (so), vastus medialis (vm), vastus lateralis (vl), rectus femoris (rf), biceps femoris (bf). Questionnaires were completed (Short Form 36 Health Survey (SF-36), Foot Function Index) and physical examination findings of the lower leg were documented.

Results: Senior subjects, compared to young subjects, had decreased passive ankle dorsiflexion (14° vs. 18°). Senior subjects had a higher incidence of hallux valgus deformity (43% vs. 8%), and dynamic clawing of the toes (29% vs. 8%). Other physical findings were similar between groups. Questionnaire scores were similar for both groups. |There was no difference between groups in duration of single- and double-limbed stance. Seniors, compared to young subjects, had increased muscle activity (normalized EMG signal, stance phase) in seven of eight muscles. The percentage difference was greatest in the lower leg muscles (gc=50% more active in seniors, so=30%, pl=30%, ta=15%). Upper leg activity was moderately increased: vm=15%, rf=6%, vl=6%. Only biceps femoris had decreased activity (−15%). Further analysis of EMG intensity, kinematics and kinetics are pending.

Conclusions: This study shows that even in healthy, active subjects, the foot and ankle is subtly altered with increasing age. Increased muscle activity may be a compensatory mechanism (i.e., to maintain overall performance). While our findings require further explanation, the characteristics documented in this study are in contrast to the shuffling gait often ascribed to older persons.