Sex Differences in Skeletal Muscle

Question 1

What is biological sex?

Answer 1

• Sex assigned at birth

Question 2

Compare female and male body compositon

Answer 2

• Males tend to have a higher % of muscle tissue
• Women have a higher % of essential and non-essential fats
• Males have a higher bone density
• ## Males may have a higher resting metabolic rate

Question 3

Describe the muscle fibre differences between sexes

Answer 3

• Strength and size of myscle differs between the sexes
• Similar pattern in old and young fibres
• Fibre distribution varies between males and females
• Dependent on the muscle

Question 4

Describe the strength and size of muscles between sexes

Answer 4

• Males tend to have larger and stronfer muscles compared to females
• When presented as a relative % difference are reduced
• Females are more fatigue resistant, possibly due to differences in fibre type distribution
• Fatigue differences are task specific

Question 5

Describe sex hormone profiles in relation to skeletal muscle

Answer 5

• Sex hormones can cross the blood brain barrier
• They can affect some of the nerve signal release from the brain to the muscle and impact how we use them

Question 6

Explain the difference in motor units and firing rates between sexes

Answer 6

• Men have a stronger muscle/force than women
• Firing rate was identified to be different between the sexes
• Motor unit potential = smaller at both contraction levels in females than males
• Recruitment strategies between contraction level are similar between sexes

Question 7

What are some significant findings of testosterone’s role in SKM?

Answer 7

• Has an anabolic impact on SKM
• Dehydroepiandrosterone (DHEA), DHEAS, the precursors of T (DHT), progressively decrease with ageing
• Some of the associated sex hormones demonstrate associations with MU firing rate

Question 8

What role does the menstrual cycle play in SKM?

Answer 8

• Can be used to identify the key parameters of muscle function that sex hormones may influence
• Number of key stages of MC are already eluded to
• No difference in muscular performance
• Differences at low level contractions firing rate but not firing rate variability
• Possibel influence of hormones at low level contractions
• Suggest a stronger influence of progesterone over oestrogen

Question 9

What are some muscle changes with age?

Answer 9

• Muscle reduces in size and strength with age
• Neuromuscular capacity of muscle also changes with age

Question 10

What is the correlation of exercise and muscle?

Answer 10

• Exercise can alleviate some of the muscle loss with age
• Both males and females can gain advantages in muscle no matter when they take up exercise

Question 11

Explain the role of neuromuscular function in exercise and muscle

Answer 11

• Long-term athletic training does not prevent age-related loss of muscle size, regardless of athletic discipline
• Physical activity into older age may facilitare more successful axxonal sprouting and reinervation of denervated dibres, preventing rapid loss of muscle strength
• These benefits may be localised to muscle most involved in the exercise regime

Question 12

Describe middle age and its influence on SKM

Answer 12

• Majority of declines begin to occur here
• Similar betwen men and women but firing rate differs
• Sex hormones could also influence neuromuscular adaptationns to exercise across the life span
• Menopause - key stage of life