Muscle Damage, Fatigue, and Circadian Rhythm

Flashcards about Muscle Damage, Fatigue, and Circadian Rhythm

What factors influence circadian rhythms?

Fluctuations in factors influenced by endogenous factors, exogenous factors, sleep-wake cycle, and an internal body clock.

How does body temperature vary throughout the day?

Body temperature is higher in the evening than in the morning.

What are possible reasons for improved anaerobic exercise and muscle strength with higher body temperatures?

Increased carbohydrate utilization, increased calcium release, and reduced concentration of inorganic phosphate.

What other factors, besides body temperature, might regulate circadian exercise performance?

Factors independent of heat may regulate circadian exercise performance, particularly in regards to power and/or strength.

How is rating of perceived exertion (RPE) affected by time of day?

Conflicting results exist; RPE has been found to be lower in the morning, evening, or show no difference during a Wingate test.

Define muscle fatigue.

The failure to maintain a required or expected power output, reversible with rest.

According to Nicolas et al., how does diurnal variation in muscle fatigue during 50 MVC reflect?

First, greater contractile capacity at 18:00 h. Second, higher fatigability at 18:00 h.

According to Lericollais et al. how does the 60 second wingate test decrement muscle power?

decrement in muscle power during a 60-second Wingate test defined at two phases: (i) First 20 sec, (ii) 21 to 60 sec. First 20 sec of the exercise power values higher at 18:00

According to Racinais et al., what explains higher torque and power decrements observed in the afternoon?

Likely a mathematical/statistical consequence of a greater initial torque or power output in the afternoon as compared to morning .

How are biochemical markers of muscle fatigue affected by time of day?

Blood lactate and glucose responses to exercise were higher in the evening than in the morning.

What is the central clock?

Suprachiasmatic nucleus (SCN) of the brain

What is the perpherial clock?

Skeletal muscle and bone

Name two proteins that contribute to a large number of clock-controlled genes.

Circadian locomotor output cycles kaput (CLOCK) and brain and muscle aryl hydrocarbon receptor nuclear translocator–like 1 (BMAL1) proteins.

How are exercise performance and health associated with the clock genes?

Exercise is known to re-set clock genes = timed exercise MAY help to re-set the daily clock and improve pathologically deteriorating circadian rhythms.

How does Circadian misalignment affect the body?

Circadian misalignment results in disturbed energy metabolism and insulin resistance in skeletal muscle.

How does the disruption of the Muscle clock affect the body?

Muscle clock disruption causes loss of BMAL1- dependent activation and REV-ERB- dependent repression of target genes.

How can exercise and diet affect the expression of skeletal muscle clock genes?

Exercise and diet are important factors that can influence the expression of skeletal muscle clock genes.