Ageing reduces light touch and vibrotactile sensitivity on the anterior lower leg and foot dorsum
Cutaneous mechanoreceptors in the anterior lower leg and foot dorsum provide important information about contact with objects and movement at the knee and ankle. This cutaneous feedback contributes to static and dynamic balance control. We conducted experiment 1 to determine the effects of ageing on anterior lower leg cutaneous feedback. We measured light touch (monofilament) perceptual thresholds (MPT) at seven skin sites across the anterior lower leg and foot dorsum in 12 young (5 male, aged 21–28) and 13 older adults (8 male, aged 73–92). Results showed that older adults had ˜ 5.5 × higher MPTs across these skin sites. We conducted experiment 2 to probe how different cutaneous mechanoreceptor subtypes are affected by ageing through measures of vibrotactile perceptual threshold (VPT) at 3, 15, and 40 Hz at six skin sites across the anterior lower leg and foot dorsum in 10 young (5 male, aged 21–26) and 10 older adults (3 male, aged 75–85). In this group, we also assessed functional balance using the timed-up-and-go (TUG) and functional reach test (FRT). Older adults demonstrated significantly higher VPTs overall, and this effect was largest at 40 Hz – a frequency primarily transmitted by fast adapting cutaneous afferents. Furthermore, higher thresholds at each frequency tended to correlate with poorer performance on the TUG within the older adult group (3 Hz: r = 0.550; 15 Hz: r = 0.689; 40 Hz: r = 0.663). These results suggest ageing influences cutaneous feedback from regions of the lower leg that provide important information about movement and contact.