Journal Club 1 - Menstrual Cycle Phase on MPS

Question 1

What was the key concept / title of this paper?

Answer 1

Looking at how menstrual cycle phase influences muscle protein synthesis or whole body myofibrillar proteolysis in response to resistance exercise

Question 2

BACKGROUND
Why was this research conducted?

Answer 2

Sex-bias in literature excluding premenopausal females from research due to menstrual cycle hormones affecting metabolic, performance or muscle-based outcomes

Question 3

What is the physiological rationale to this research?

Answer 3

• Oestrogen signalling may be involved in pathways influences muscular adaptations to exercise
• Ovarian hormones may inhibit protein turnover + muscle growth
• Alteration in cycle hormones influence protein catabolism

Question 4

What was the study-design?

Answer 4

Cross-over design

• unilateral resistance exercise + integrated 5 day assessments of protein turnover

Question 5

What 2 phases were female subjects assessed in?

Answer 5

1. Late follicular phase - highest E2 (oestradiol) conc
2. Mid-luteal phase - highest P4 (progesterone) conc

Question 6

How did they determine which phase the females were in?

Answer 6

Late follicular phase - 5 days prior to predicted ovulation based on timing of positive urinary ovulation phase

Mid-luteal phase - 5 days following positive urinary ovulation test

Question 7

What did the exercise consist of/

Answer 7

3 sets of 10 unilateral knee extensions to volitional fatigue

Question 8

How were muscle protein synthesis (MPS) rates quantified?

Answer 8

Incorporation of deuterium into muscle-protein bound alanine

• determined using standard precursor-product method

Question 9

What did the study find about muscle protein synthesis (MPS) across the menstrual cycle

Answer 9

MPS increased after resistance exercise equally in both follicular and luteal phases

Question 10

What does the finding on MPS suggest about hormonal influence?

Answer 10

Oestrogen and progesterone fluctuations do not impair the muscle’s anabolic response to exercise

Question 11

What did the study find about muscle protein breakdown (MPB) or proteolysis

Answer 11

Whole-body myofibrillar proteolysis was unchanged across menstrual cycle phases

Question 12

What was observed in blood metabolite profiles during different menstrual phases

Answer 12

No phase-specific differences in amino acid or protein metabolism-related metabolites

Question 13

How does this study contribute to our understanding of protein metabolism in women

Answer 13

It shows that the ability to synthesise and break down muscle proteins is stable across the menstrual cycle