Exercise temperature regulation following a 35-day horizontal bedrest.

Area of Science:

• Exercise Physiology
• Human Physiology
• Thermoregulation

Background:

• Prolonged bed rest leads to cardiovascular and muscular deconditioning.
• Deconditioning may affect the body's ability to manage heat during physical activity.
• Understanding thermoregulatory responses post-bed rest is crucial for recovery protocols.

Purpose of the Study:

• To investigate the impact of 35-day horizontal bed rest on thermoeffector responses during submaximal exercise.
• To determine if bed rest alters body core temperature regulation during cycling at fixed absolute and relative intensities.
• To identify potential impairments in heat loss mechanisms following prolonged inactivity.

Main Methods:

• Fifteen healthy men were divided into bed rest (BR) and control (CON) groups.
• The BR group underwent 35 days of horizontal bed rest.
• Thermoregulatory responses (rectal temperature, skin temperature, sweating rate) were measured during cycling exercise before and after bed rest at fixed absolute and relative intensities.

Main Results:

• Bed rest moderately increased core body temperature during exercise at a fixed absolute intensity (POST-A).
• No significant temperature increase was observed during exercise at a fixed relative intensity (POST-R).
• Skin temperature was lower and forehead sweating rate was similar across post-bed rest trials, suggesting impaired non-evaporative heat loss.

Conclusions:

• A 35-day bed rest period can exacerbate the rise in core body temperature during exercise at a fixed absolute intensity.
• This effect is likely due to impaired non-evaporative heat loss resulting from deconditioning.
• Thermoregulatory responses are influenced by exercise intensity relative to the deconditioned state.