Sex Differences in Muscle Damage Following Resistance Exercise With or Without Milk Protein Ingestion (EIMD-MILK)

Sex Differences in Resistance Exercise-induced Muscle Damage: The Impact of Milk Protein Ingestion

Purpose: To investigate the impact of milk protein ingestion on resistance exercise-induced muscle damage in untrained males and females.

Rationale: Unaccustomed resistance exercise can cause muscle damage, presenting as muscle soreness and reduced muscle function - such as loss of strength, power, and flexibility - for several days after the exercise bout. Therefore, individuals may require longer recovery periods before performing another exercise bout, and their performance may be impaired. Further, muscle soreness may reduce exercise compliance, particularly in novice individuals. Over time, this may compromise the gains in muscle mass and strength achieved through exercise training. Therefore, strategies to reduce the severity of exercise-induced muscle damage and/or to enhance post-exercise recovery processes are advantageous for exercising individuals.

One such strategy is the consumption of dietary protein before or after muscle-damaging exercise, which has shown to alleviate muscle soreness, improve blood markers of muscle damage, and reduce the decline in maximal force and flexibility. In particular, consuming 20-gram doses of milk protein in the days after resistance exercise can improve the recovery time of muscle soreness and maximum force, and also lower levels of damage markers in the blood. However, most studies have been conducted with male participants who are well-trained in resistance exercise. It has been suggested that males and females respond differently to muscle damage, and therefore, this research aims to provide a sex comparison in the muscle damage response to an acute bout of resistance exercise with or without milk protein feeding.

Therefore, 40 healthy, young (18-35 years) adults (20 males, 20 females) will be recruited to participate in this randomised controlled trial. Maximal leg strength and body composition (by dual-energy X-ray absorptiometry; DXA) will be conducted at baseline. In females, all primary outcome measures will be obtained during the late follicular phase of the menstrual cycle. Participants will then be randomised to a protein (dairy yoghurt) or placebo (oat-based yoghurt) dietary condition.

Three weeks later, participants will complete a high-intensity resistance exercise session on leg extension and leg curl machines to induce muscle damage. Various measures of muscle damage (blood biomarkers, muscle soreness, flexibility, and swelling) will be obtained before, immediately after, and 24, 48, 72, and 168 h after the exercise protocol. The maximal strength test will be repeated 72 and 168 h after the exercise. Participants will consume the protein or placebo yoghurt 4 times per day (every 3-4 hours) on the day of the exercise bout and the following 3 days. Participants' habitual activity and dietary intake will be monitored and controlled throughout the study period.

Expected outcome: It is expected that the resistance exercise protocol will induce muscle damage, which will be attenuated with the ingestion of milk protein. It cannot be ascertained whether males and females will have the same responses to the exercise or to protein ingestion.

Study Overview

• Status: Recruiting
• Conditions: Muscle Damage
• Intervention / Treatment: Other: Resistance exercise

• Study Type: Interventional
• Enrollment (Anticipated): 40
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Alice G Pearson; Phone Number: 07771357222; Email: alice.g.pearson@durham.ac.uk
• Study Contact Backup: Name: Lindsay S Macnaughton; Email: lindsay.s.macnaughton@durham.ac.uk

Study Locations

• United Kingdom
  • Durham, United Kingdom, DH1 3HN
    • Recruiting
    • Durham University, Sports and Wellbeing Park
    • Contact: Alice G Pearson; Phone Number: 07771357222; Email: alice.g.pearson@durham.ac.uk
    • Contact: Lindsay S Macnaughton; Email: lindsay.s.macnaughton@durham.ac.uk

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 35 years (ADULT)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• BMI 18.5 - 25.0 kg/m2
• Untrained in resistance exercise
• No known chronic disease or current acute illness
• No current or recent (past 3 months) musculoskeletal injury
• No frequent use (2x per week for past month) of non-steroidal anti-inflammatory drugs and compliant to abstain from use during experimental period
• No recent or current engagement in massage or cryotherapy and compliant to abstain from use during experimental period
• No current use of protein or antioxidant supplements
• Are able to consume dairy products (i.e., not lactose-intolerant or vegan)
• Females will be eumenorrheic (regular menstrual cycle) >12 months
• Absence of pregnancy and breast-feeding

Exclusion Criteria:

• Underweight
• Overweight/obese
• Resistance trained
• Current or recent injury
• Pregnancy or breast-feeding
• Lactose intolerant
• Unwilling to provide blood samples, perform resistance exercise, or abstain from use of NSAID's and protein supplementation (unless instructed as part of the research)
• Unwilling to abstain from other forms of exercise during the experimental period

Study Plan

How is the study designed?

Design Details

• Primary Purpose: BASIC_SCIENCE
• Allocation: RANDOMIZED
• Interventional Model: PARALLEL
• Masking: TRIPLE

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
EXPERIMENTAL: Milk Protein; 4 daily 20-gram doses of milk protein (dairy yoghurt) consumed for 4 consecutive days after the exercise bout	Other: Resistance exercise; Acute leg-based resistance exercise bout performed at 80% 1RM (4 sets to volitional failure on leg extension and leg curl machines)
PLACEBO_COMPARATOR: Placebo; 4 daily doses of low-protein placebo product (oat-based yoghurt) consumed for 4 consecutive days after the exercise bout	Other: Resistance exercise; Acute leg-based resistance exercise bout performed at 80% 1RM (4 sets to volitional failure on leg extension and leg curl machines)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Maximal Voluntary Contraction at baseline	One-repetition maximum (1RM) test: leg extension and leg curl machines	Baseline
Change from baseline Maximal Voluntary Contraction at 72-hours post-exercise	One-repetition maximum (1RM) test: leg extension and leg curl machines	72-hours after the exercise bout
Change from baseline Maximal Voluntary Contraction at 168-hours post-exercise	One-repetition maximum (1RM) test: leg extension and leg curl machines	168-hours after the exercise bout
Creatine kinase concentration at baseline	Serum concentration of creatine kinase from venous blood sampling	Immediately pre-exercise
Change from baseline in Creatine Kinase concentration immediately post-exercise	Serum concentration of creatine kinase from venous blood sampling	Immediately after the exercise bout
Change from baseline in Creatine Kinase concentration at 24-hours post-exercise	Serum concentration of creatine kinase from venous blood sampling	24-hours after the exercise bout
Change from baseline in Creatine Kinase concentration at 48-hours post-exercise	Serum concentration of creatine kinase from venous blood sampling	48-hours after the exercise bout
Change from baseline in Creatine Kinase concentration at 72-hours post-exercise	Serum concentration of creatine kinase from venous blood sampling	72-hours after the exercise bout
Change from baseline in Creatine Kinase concentration at 168-hours post-exercise	Serum concentration of creatine kinase from venous blood sampling	168-hours after the exercise bout
Interleukin-6 concentration at baseline	Serum concentration of Interleukin-6 from venous blood sampling	Immediately pre-exercise
Change from baseline in Interleukin-6 concentration immediately post-exercise	Serum concentration of Interleukin-6 from venous blood sampling	Immediately after the exercise bout
Change from baseline in Interleukin-6 concentration at 24-hours post-exercise	Serum concentration of Interleukin-6 from venous blood sampling	24-hours after the exercise bout
Change from baseline in Interleukin-6 concentration at 48-hours post-exercise	Serum concentration of Interleukin-6 from venous blood sampling	48-hours after the exercise bout
Change from baseline in Interleukin-6 concentration at 72-hours post-exercise	Serum concentration of Interleukin-6 from venous blood sampling	72-hours after the exercise bout
Change from baseline in Interleukin-6 concentration at 168-hours post-exercise	Serum concentration of Interleukin-6 from venous blood sampling	168-hours after the exercise bout
Muscle soreness (pressure algometry) at baseline	Self-perceived rating of muscle soreness with use of pressure algometry	Immediately pre-exercise
Change in muscle soreness (pressure algometry) immediately post-exercise	Self-perceived rating of muscle soreness with use of pressure algometry	Immediately after the exercise bout
Change in muscle soreness (pressure algometry) at 24-hours post-exercise	Self-perceived rating of muscle soreness with use of pressure algometry	24-hours after the exercise bout
Change in muscle soreness (pressure algometry) at 48-hours post-exercise	Self-perceived rating of muscle soreness with use of pressure algometry	48-hours after the exercise bout
Change in muscle soreness (pressure algometry) at 72-hours post-exercise	Self-perceived rating of muscle soreness with use of pressure algometry	72-hours after the exercise bout
Change in muscle soreness (pressure algometry) at 168-hours post-exercise	Self-perceived rating of muscle soreness with use of pressure algometry	168-hours after the exercise bout
Muscle soreness (VAS) at baseline	Self-perceived rating of muscle soreness while performing a bodyweight squat with use of a visual analogue scale	Immediately pre-exercise
Change in muscle soreness (VAS) immediately post-exercise	Self-perceived rating of muscle soreness while performing a bodyweight squat with use of a visual analogue scale	Immediately after the exercise bout
Change in muscle soreness (VAS) at 24-hours post-exercise	Self-perceived rating of muscle soreness while performing a bodyweight squat with use of a visual analogue scale	24-hours after the exercise bout
Change in muscle soreness (VAS) at 48-hours post-exercise	Self-perceived rating of muscle soreness while performing a bodyweight squat with use of a visual analogue scale	48-hours after the exercise bout
Change in muscle soreness (VAS) at 72-hours post-exercise	Self-perceived rating of muscle soreness while performing a bodyweight squat with use of a visual analogue scale	72-hours after the exercise bout
Change in muscle soreness (VAS) at 168-hours post-exercise	Self-perceived rating of muscle soreness while performing a bodyweight squat with use of a visual analogue scale	168-hours after the exercise bout
Range of motion at baseline	Flexibility of the exercised limb as determined by goniometry	Immediately pre-exercise
Change in range of motion immediately post-exercise	Flexibility of the exercised limb as determined by goniometry	Immediately after the exercise bout
Change in range of motion at 24-hours post-exercise	Flexibility of the exercised limb as determined by goniometry	24-hours after the exercise bout
Change in range of motion at 48-hours post-exercise	Flexibility of the exercised limb as determined by goniometry	48-hours after the exercise bout
Change in range of motion at 72-hours post-exercise	Flexibility of the exercised limb as determined by goniometry	72-hours after the exercise bout
Change in range of motion at 168-hours post-exercise	Flexibility of the exercised limb as determined by goniometry	168-hours after the exercise bout
Limb circumference at baseline	Measure of leg circumference with use of standard anthropometric tape to indicate muscle swelling	Immediately pre-exercise
Change in limb circumference immediately post-exercise	Measure of leg circumference with use of standard anthropometric tape to indicate muscle swelling	Immediately after the exercise bout
Change in limb circumference at 24-hours post-exercise	Measure of leg circumference with use of standard anthropometric tape to indicate muscle swelling	24-hours after the exercise bout
Change in limb circumference at 48-hours post-exercise	Measure of leg circumference with use of standard anthropometric tape to indicate muscle swelling	48-hours after the exercise bout
Change in limb circumference at 72-hours post-exercise	Measure of leg circumference with use of standard anthropometric tape to indicate muscle swelling	72-hours after the exercise bout
Change in limb circumference at 168-hours post-exercise	Measure of leg circumference with use of standard anthropometric tape to indicate muscle swelling	168-hours after the exercise bout

Collaborators and Investigators

• Sponsor: Durham University

Study record dates

Study Major Dates

• Study Start (ACTUAL): August 31, 2021
• Primary Completion (ANTICIPATED): September 1, 2022
• Study Completion (ANTICIPATED): September 1, 2022

Study Registration Dates

• First Submitted: June 30, 2021
• First Submitted That Met QC Criteria: July 22, 2021
• First Posted (ACTUAL): August 2, 2021

Study Record Updates

• Last Update Posted (ACTUAL): October 27, 2021
• Last Update Submitted That Met QC Criteria: October 26, 2021
• Last Verified: October 1, 2021

More Information

Terms related to this study

• Keywords: Resistance exercise; Dietary protein; Muscle soreness; Milk protein; Sex differences; Exercise-induced muscle damage
• Other Study ID Numbers: 290580A

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No