Effects of Protein and NAC Co-ingestion on Skeletal Muscle Recovery (PRoNAC)

Effects of Whey Protein and N-acetylcysteine Co-ingestion on Skeletal Muscle Recovery Following Exercise-induced Muscle Damage.

Previous evidence suggests that though N-acetylcysteine (NAC) supplementation following eccentric exercise-induced muscle damage disrupts the skeletal muscle's repair and remodelling process at 8 days of recovery, it attenuates substantially the decline of skeletal muscle performance during the first 48 hours of recovery. The enhanced performance capacity during the first phase of recovery in response to NAC supplementation might be attributed to the altered redox status in skeletal muscle as a consequence of the NAC-mediated elevation of reduced glutathione (GSH) levels. The rise in GSH results in a redox-dependent attenuation of immune cell mobilisation and reduction of oxidative stress response, leading to a blunted rise of muscle damage and inflammatory markers during the first 2-3 days of recovery. However, following exercise-induced muscle damage, protein synthesis increases in skeletal muscle over the next 24-48 hours to support its repair process, and thus protein supplementation might accelerate the recovery process by enhancing the protein synthetic response. Therefore, the present study aims at investigating for first time the combined effect of NAC and whey protein supplementation on the short-term (during the first 72 hours) recovery process of skeletal muscle following damaging exercise (eccentric exercise) and compared it with the well-documented efficacy of NAC supplementation. The results of this study might be particularly useful for athletes, such as those in soccer and basketball, that participate in 3 games or intense training sessions during the same macrocycle with only 48-72 hours of recovery in-between.

Study Overview

• Status: Recruiting
• Conditions: Aseptic Muscle Injury
• Intervention / Treatment: Dietary supplement: Placebo; Dietary supplement: NAC; Dietary supplement: NAC + Whey Protein

Detailed Description

Participants will initially undergo baseline testing including assessment of their (i) anthropometrics, (ii) body composition via DXA, (iii) habitual physical activity level via accelerometry, (iv) resting metabolic rate via indirect calorimetry, (v) daily dietary intake via 7-day dietary recalls and (vi) cardiorespiratory fitness using a treadmill ramp test. After baseline testing, participants will be assigned to (a) a Placebo, (b) a N-acetylcysteine (NAC) or (c) a N-acetylcysteine + Whey protein (PRoNAC) group, in a randomized, double-blind, placebo-controlled, parallel group, repeated measures design. In all groups, participants will execute an eccentric exercise protocol on an isokinetic dynamometer consisted of 150 eccentric muscle contractions. Before exercise as well as at 1-, 2-, 3-, 24-, 48- and 72-hours post-exercise they will undergo assessment of their maximal voluntary isometric peal torque, maximal countermovement jump height and muscle soreness level. In addition, blood sample will be drawn before exercise and at 24-, 48- and 72-hours post-exercise for the determination of myoglobin concentration, reduced (GSH) and oxidized (GSSG) glutathione content, protein carbonyl formation and catalase activity.

Throughout the 4-day experimental period (Day 1: exercise day, Days 2, 3 and 4: 24-, 48- and 72-hours post-exercise, respectively) participants will receive daily, 3 doses from the respective supplement as follows: the 1st dose at mid-morning (between breakfast and lunch), the 2nd dose at mid-afternoon (post-exercise on day 1 and between lunch and dinner on days 2-4) and the 3rd dose before sleep. In Placebo group, participants will be supplemented with 0.31 gr of maltodextrin per kg of body weight in the first two servings (at mid-morning and mid-afternoon supplements) and with 0.49 gr of maltodextrin per kg of body weight in the pre-sleep serving (1.1 gr maltodextrin/kg BW/day). In NAC group, participants will be supplemented with 13.33 mg of N-acetylcysteine per kg of body weight per serving (40 mg NAC/kg BW/day). In PRoNAC group participants will be supplemented with 0.31 gr of whey protein and 13.33 mg of N-acetylcysteine per kg of body weight in the first two servings (at mid-morning and mid-afternoon supplements) and with 0.49 gr of whey protein and 13.33 mg of N-acetylcysteine per kg of body weight in the pre-sleep serving (1.1 gr Whey protein + 40 mg NAC /kg BW/day).

• Study Type: Interventional
• Enrollment (Estimated): 30
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Dimitrios Draganidis, PhD; Phone Number: +30 2431047078; Email: ddraganidis@uth.gr
• Study Contact Backup: Name: Ioannis G Fatouros, PhD; Phone Number: +302431047047; Email: ifatouros@uth.gr

Study Locations

• Greece
  • Karies
    • Tríkala, Karies, Greece, 42100
      • Recruiting
      • Department of Physical Education and Sport Science, University of Thessaly
      • Contact: Dimitrios Draganidis, PhD; Phone Number: +30 2431047078; Email: ddraganidis@uth.gr
      • Contact: Ioannis G Fatouros, PhD; Phone Number: +302431047047; Email: ifatouros@uth.gr

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Free of asthma, kidney disease, bleeding disorders, peptic ulcers.
• Free of musculoskeletal injuries and limitations.
• Abstain from dietary energy restriction.
• Do not use medication such as anti-inflammatory drugs, antibiotics, antihypertensive drugs or anticoagulants.
• Do not use dietary supplements such as protein, carbohydrate, antioxidants, vitamins etc.
• Free of N-acetylcysteine intolerance.
• Non-smokers.
• Abstain from alcohol throughout the study.

Exclusion Criteria:

• Presence of asthma, kidney disease, bleeding disorders, peptic ulcers.
• Musculoskeletal injuries and limitations.
• Dietary energy restriction.
• Use of anti-inflammatory drugs, antibiotics, antihypertensive drugs or anticoagulants.
• Use of dietary supplements such as protein, carbohydrate, antioxidants, vitamins etc.
• N-acetylcysteine intolerance.
• Smoking.
• Alcohol consumption during the study.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Placebo Comparator: Placebo; Participants in this arm will execute 150 eccentric muscle contractions an receive a placebo supplement consisted of carbohydrate (maltodextrin).	Dietary supplement: Placebo; Participants will receive three servings of carbohydrate per day during the 4-day experimental period. In specific, they will be supplemented with 0.31 gr of maltodextrin per kg of body weight in the first two servings (at mid-morning and mid-afternoon supplements) and with 0.49 gr of maltodextrin per kg of body weight in the pre-sleep serving (1.1 gr maltodextrin/kg BW/day).
Experimental: NAC; Participants in this arm will execute 150 eccentric muscle contractions an receive a N-acetylcysteine supplement.	Dietary supplement: NAC; Participants will receive three servings of N-acetylcysteine per day during the 4-day experimental period. In specific, they will be supplemented with 13.33 mg of N-acetylcysteine per kg of body weight per serving (40 mg NAC/kg BW/day).
Experimental: PRoNAC; Participants in this arm will execute 150 eccentric muscle contractions an receive a supplement consisted of N-acetylcysteine and whey protein.	Dietary supplement: NAC + Whey Protein; Participants will receive three servings of N-acetylcysteine + whey protein per day during the 4-day experimental period. In specific, they will be supplemented with 0.31 gr of whey protein and 13.33 mg of N-acetylcysteine per kg of body weight in the first two servings (at mid-morning and mid-afternoon supplements) and with 0.49 gr of whey protein and 13.33 mg of N-acetylcysteine per kg of body weight in the pre-sleep serving (1.1 gr Whey protein + 40 mg NAC /kg BW/day).

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in maximal voluntary isometric muscle contraction.	Maximal voluntary isometric muscle contraction will be assessed on an isokinetic dynamometer.	Before exercise and at 1-, 2-, 3-, 24-, 48- and 72-hours post-exercise.
Change in countermovement jump height.	Countermovement jump height will be assessed by using the Optojump Next system.	Before exercise and at 1-, 2-, 3-, 24-, 48- and 72-hours post-exercise.
Change in delayed onset of muscle soreness (DOMS)	DOMS of the knee extensors of the dominant limb will be evaluated by palpation of the relaxed muscle's belly and distal region with participants rating the perceived soreness on a visual analogue scale ranging from 1 to 10.	Before exercise and at 1-, 2-, 3-, 24-, 48- and 72-hours post-exercise.
Change in reduced glutathione content.	Reduced glutathione content in blood erythrocytes will be assessed using spectrophometric method.	Before exercise and at 24-, 48- and 72-hours post-exercise.
Change in oxidized glutathione content.	Oxidized glutathione content in blood erythrocytes will be assessed using spectrophometric method.	Before exercise and at 24-, 48- and 72-hours post-exercise.
Change in catalase activity.	Catalase activity will be measured spectrophotometrically in red blood cells.	Before exercise and at 24-, 48- and 72-hours post-exercise.
Change in protein carbonyl concentration	Protein carbonyl concentration will be measured spectrophotometrically in red blood cells.	Before exercise and at 24-, 48- and 72-hours post-exercise.
Change in myoglobin concentration in blood.	Myoglobin concentration in blood will be assessed using an automatic biochemistry analyzer and commercially available kits.	Before exercise and at 24-, 48- and 72-hours post-exercise.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Participants' lean body mass	Lean body mass (kg) will be assessed using dual-energy X-ray absorptiometry (DXA) instrumentation.	At baseline.
Participants' daily physical activity-related energy expenditure.	Physical activity-related energy expenditure (kcal/day) will be assessed using accelerometers.	At baseline.
Participants daily dietary intake.	Daily dietary intake composition (total kcal/day, gr of protein, gr of CHO and gr of fat intake/day, gr/mg of micronutrient intake/day) will be monitored using 24-h dietary recalls that will be analyzed by a trained dietitian using a dietary analysis software.	At baseline.
Participants' resting metabolic rate.	Resting metabolic rate will be assessed using indirect calorimetry.	At baseline.
Participants' cardiorespiratory fitness status.	Cardiorespiratory fitness will be assessed using a treadmill ramp test.	At baseline.
Participants' fat free mass.	Fat free mass will be assessed using dual-energy X-ray absorptiometry (DXA) instrumentation.	At baseline.
Participants' fat mass.	Fat mass will be assessed using dual-energy X-ray absorptiometry (DXA) instrumentation.	At baseline.
Participants' body fat percent.	Body fat percent (%) will be assessed using dual-energy X-ray absorptiometry (DXA) instrumentation.	At baseline.

Collaborators and Investigators

• Sponsor: University of Thessaly
• Investigators: Principal Investigator: Dimitrios Draganidis, PhD, University of Thessaly, Department of Physical Education and Sport Science

Study record dates

Study Major Dates

• Study Start (Actual): April 8, 2024
• Primary Completion (Estimated): June 30, 2025
• Study Completion (Estimated): July 30, 2025

Study Registration Dates

• First Submitted: April 7, 2024
• First Submitted That Met QC Criteria: April 11, 2024
• First Posted (Actual): April 16, 2024

Study Record Updates

• Last Update Posted (Actual): June 4, 2025
• Last Update Submitted That Met QC Criteria: May 31, 2025
• Last Verified: January 1, 2025

More Information

Terms related to this study

• Other Study ID Numbers: UTH-PRoNAC Study

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No