Plantarflexion Strength of the Toes: Age and Gender Differences and Evaluation of a Clinical Screening Test

Background: The toes play an important stabilizing role in weightbearing activities. However, the factors that influence toe plantarflexion strength are poorly understood, and there are no validated measures for assessing toe weakness in the clinical setting. Therefore, the objectives of this study were to determine whether plantarflexion strength of the toes differs according to age and gender and to evaluate the validity of a clinical screening test for assessing toe plantarflexor weakness (the paper grip test). Methods: Plantarflexion strength of the hallux and lesser toes was measured in 40 young participants (20 men and 20 women, mean age 20.8 ± 2.2 years) and 40 older participants (20 men and 20 women, mean age 74.6 ± 5.7 years) using a pressure platform in conjunction with clinical assessment using the paper grip test. Results: Older participants exhibited 32% less plantarflexion strength of the hallux and 27% less plantarflexion strength of the lesser toes compared to younger participants, and women exhibited 42% less hallux plantarflexor strength than men. Gender did not influence lesser toe plantarflexor strength. Participants who failed the paper grip test exhibited significantly reduced plantarflexion strength for both the hallux and lesser toes. The sensitivity and specificity of the paper grip test of the hallux to predict plantarflexor strength less than 2.6 kg was 80% and 79%, respectively, and the sensitivity and specificity of the paper grip test of the lesser toes to predict plantarflexor strength less than 2.2 kg was 75% and 74%, respectively. Conclusions: These findings indicate that aging is associated with reduced plantarflexion strength of the toes. The paper grip test may be a useful screening tool to detect toe weakness in the clinical setting.