Age-related reduction and independent predictors of toe flexor strength in middle-aged men

Abstract

Background: Toe flexor muscles play an important role in posture and locomotion, and poor toe flexor strength is a risk factor for falls. In this cross-sectional study, we estimated the age-related change in toe flexor strength and compared it with that of handgrip strength. Independent factors predicting toe flexor and handgrip strength were also determined.

Methods: A total of 1401 male (aged 35-59 years) study participants were divided into five groups according to their chronological age; 35-39, 40-44, 45-49, 50-54, and 55-59 years. Toe flexor and handgrip strength, anthropometry, and resting blood pressure were measured. Fasting blood samples were collected to measure blood glucose, triglycerides, high- and low-density lipoprotein-cholesterols, and albumin. A self-administered lifestyle questionnaire was conducted.

Results: Decline in absolute toe flexor and handgrip strength began in the age groups 50-55 and 55-59 years, respectively. In comparison to the mean values of the youngest group, relative toe flexor strength (87.0 ± 26.6%) was significantly lower than handgrip strength (94.4 ± 13.1%) for the oldest group. Multiple regression analyses showed that independent factors predicting both toe flexor and handgrip strength were lean body mass, age, serum albumin, drinking habit, and fat mass. Additionally, fasting blood glucose, diastolic blood pressure, sleeping time and exercise habit were predicting factors of toe flexor strength but not of handgrip strength.

Conclusions: Age-related reduction in toe flexor strength was earlier and greater than handgrip strength, and toe flexor strength reflects body composition and metabolic status.

Keywords: Aging; Blood pressure; Handgrip; Hyperglycemia; Skeletal muscle; Toe flexion.

Fig. 1

Measurement of toe flexor strength. a the toe grip dynamometer and parts of the instrument. b test of toe flexor strength using a toe grip dynamometer. The subject sits on a chair with their trunk in the vertical position and hip and knee joints flexed at approximately 90°. One foot is placed on the dynamometer, and the first proximal phalanx of the foot is positioned on a grip bar with the heel position fixed using a heel stopper and immobilization belt

Fig. 2

Relative differences between toe flexor and handgrip strength from the youngest group. Data are presented as mean ± SD. * P < 0.05 vs. handgrip strength