Effects of increasing temperature in different foot regions on foot sensitivity and postural control in young adults

Pilot study of musculoskeletal discomfort in Indonesian pregnant workers during COVID-19 pandemic era

Objective

This pilot study aims to analyze the factors influencing musculoskeletal discomfort in pregnant workers in Indonesia from occupational aspects, especially during the pandemic, to recommend further interventions and policies for a safer and healthier workplace.

Methods

This study was a cross-sectional study. It used an online questionnaire to collect data on individual, occupational, and work environmental factors and musculoskeletal discomfort. We used Chi-square and logistic regression analysis to determine associations between the risk factors and the musculoskeletal discomfort.

Results

A total of 126 women from multiple employment sectors participated. About 59% of respondents reported discomfort, with the majority having pain in the lower back (62.2%). Chi-square analysis revealed that age, history of injury, subjective agility and speed, length of working days in a week, and subjective temperature conformity were associated with the prevalence of musculoskeletal discomfort. Logistic regression revealed that age (p = 0.018 and OR = 2.218) and temperature conformity (p = 0.049 and OR = 2.157) were the most significant independent predictors of musculoskeletal discomfort.

Conclusion

This study shows that temperature conformity is a predictor of musculoskeletal discomfort. Employers should consider this when determining whether their workplace is suitable for pregnant women. The treatment of younger workers needs attention, especially during pregnancy, they may need extra accommodation during pregnancy.

Effects of triceps surae exercise-induced delayed onset muscle soreness on control of body stability in different postures

This research aimed to determine whether triceps surae delayed onset muscle soreness (DOMS) affects stability while performing different postural control tasks requiring upright and landing stabilization. Twenty-four participants who self-reported as healthy were recruited. Pre and 48 h after a protocol to induce DOMS in the triceps surae, participants were evaluated for DOMS perception, pressure pain threshold, and postural control (assessed by the center of pressure, CoP) during different standing and landing stabilization tasks. We found higher DOMS perception and lower pressure pain threshold 48 h after the exercise. Mediolateral CoP displacement was more sensitive to DOMS across different postural tasks, but no effects were found for bilateral standing. The landing time to stabilization elicited high individual variability in the presence of DOMS. Effects of DOMS in the performance of less challenging tasks, such as bipedal standing, were not found. We conclude that DOMS in the triceps surae impairs mediolateral postural control during challenging tasks such as unilateral standing and body forward lean. It highlights the need for caution and individualized approaches when incorporating movements requiring frontal plane control in training and rehabilitation sessions under the presence of DOMS.

Heating the skin on the foot sole enhances cutaneous reflexes in the lower limb

Cutaneous input is important in postural control and balance. Aging and diabetes impair skin sensitivity and motor control. Heat application can improve skin sensation, but its influence on motor control remains unknown. This study investigated the effects of heating the skin of the foot sole on lower limb cutaneous reflexes. Reflexes were evoked in the tibialis anterior muscle of 20 young, healthy adults before and after heating the foot sole to a maximum of 42°C. While holding a 15% maximum root mean square EMG generated during maximum isometric dorsiflexion, a filtered white noise (0-50 Hz) vibration at 10 times the perceptual threshold was applied to the heel to stimulate cutaneous mechanoreceptors. Reflexes were analyzed in both the time (cumulant density) and frequency (coherence, gain) domains. Heat increased foot skin temperature ∼15.4°C (P < 0.001). Cumulant density peak to peak amplitude significantly increased by 44% after heating (P = 0.01) while latencies did not vary (P = 0.46). Coherence and gain were significantly greater in the 30- to 40-Hz range following heating (P = 0.048; P = 0.02). Heating significantly enhances lower limb cutaneous reflexes. This may be due to the increased ability of cutaneous mechanoreceptors to encode in the 30- to 40-Hz range.NEW & NOTEWORTHY Cutaneous input is a known modulator of muscle activity. Targeting skin to intentionally enhance motor output has received little attention. We explored local skin heating to enhance skin sensitivity and found a significant increase in the amplitude, coherence, and gain of cutaneous reflexes in the tibialis anterior. Our current findings provide the first support for the use of heat as a viable and easily integrated modality in rehabilitation technology to improve balance and postural control.

Short-term foot warming impacts foot sensitivity and body sway differently in older adults

BACKGROUND

Aging is accompanied by loss of foot skin sensitivity and reduced postural control. Increasing foot temperature can improve both skin sensitivity and postural control in adults. However, it remains unclear whether similar effects can be observed in older adults.

RESEARCH QUESTION

Can foot warming improve postural control in older adults, similar to observations in younger adults?

METHODS

Two foot warming protocols were conducted in 18 older adults (14 women, 4 men) to increase foot temperature by using infrared radiation to (1) warm the plantar aspect and (2) the skin of the entire foot and ankle area. We assessed the foot skin sensitivity before and after warming, considering tactile stimulation and center of pressure (CoP) displacement during 30-s standing with eyes open and closed.

RESULTS AND SIGNIFICANCE

Both foot warming protocols led to similar increases in skin temperature (∼6 °C) compared to the basal condition, but only warming the entire foot and ankle area increased foot sensitivity for the different regions assessed. No main effects or interactions were found for CoP variables in response to the two warming protocols. The short-term effects identified after warming the entire foot and ankle region suggest that this might be a strategy to improve skin sensitivity in older adults as observed in younger adults, but this was not the case for CoP. Future research should clarify whether the magnitude and long-lasting effects of warming could be determinant of CoP results.