Nutritional strategies before exercise play a vital role in enhancing physical performance and facilitating post-exercise recovery, especially in resistance-trained individuals. Among the most common pre-exercise supplements are carbohydrates (CHO) and proteins (PRO), both of which serve distinct physiological functions. Carbohydrates are the primary source of energy during high-intensity exercise, helping to maintain blood glucose levels and delay fatigue (1). Protein, on the other hand, is crucial for muscle protein synthesis, repair of muscle tissue, and attenuation of muscle damage following resistance exercise (2,3).

Although carbohydrate intake before exercise has been widely recommended for performance enhancement, recent evidence suggests that protein ingestion may also offer performance benefits when consumed pre-exercise, particularly through its anti-catabolic and recovery-promoting effects (4,5). Some studies report that protein taken before training may increase muscle protein synthesis rates and reduce markers of muscle damage compared to carbohydrate supplementation (6,7). However, findings remain inconsistent across different training protocols and populations.

In resistance-trained individuals, where muscle recovery and strength gains are primary goals, understanding the optimal pre-exercise supplement becomes crucial. While both nutrients contribute to performance and recovery, their comparative effectiveness when taken pre-workout has not been thoroughly explored. Hence, this study aims to compare the effects of pre-exercise carbohydrate versus protein supplementation on muscle recovery and performance in resistance-trained males.

Study Design and Participants:

This randomized controlled trial was conducted over a period of six weeks and included 40 healthy, resistance-trained male participants aged between 20 and 30 years. Inclusion criteria required participants to have at least one year of consistent resistance training experience, no history of metabolic or musculoskeletal disorders, and not currently using any performance-enhancing supplements.

Randomization and Group Allocation:

Participants were randomly assigned into two equal groups (n = 20 each) using a computer-generated randomization table. Group 1 (CHO group) received a carbohydrate supplement, and Group 2 (PRO group) received a protein supplement, both administered 30 minutes prior to exercise sessions.

Supplementation Protocol:

The CHO group consumed 50 grams of maltodextrin dissolved in 300 ml of water. The PRO group consumed 30 grams of whey protein isolate mixed in 300 ml of water. Supplements were isocaloric and were provided on-site under supervision to ensure compliance.

Training Protocol:

All participants followed a standardized full-body resistance training program three times per week. The routine included compound and isolation exercises targeting all major muscle groups, with progressive overload applied weekly. Each session consisted of 3–4 sets of 8–12 repetitions per exercise with 60–90 seconds of rest between sets.

Outcome Measures:

The primary outcomes were muscle recovery and performance. Muscle soreness was assessed using a 10-point visual analogue scale (VAS) 24 hours post-exercise. Blood samples were collected pre- and post-intervention to measure serum creatine kinase (CK) levels as a marker of muscle damage. Performance was evaluated using one-repetition maximum (1RM) tests for bench press and squat at baseline and at the end of the intervention.

Statistical Analysis:

Data were analyzed using SPSS version 25.0. Descriptive statistics were calculated for all variables. Paired t-tests were used to compare pre- and post-intervention scores within groups, while independent t-tests compared outcomes between groups. A p-value < 0.05 was considered statistically significant.

All 40 participants completed the study without adverse events. The baseline characteristics including age, weight, and training experience were similar between the carbohydrate (CHO) and protein (PRO) groups (p > 0.05).

Muscle Soreness (VAS Score):

After the 6-week intervention, the PRO group reported significantly lower post-exercise muscle soreness (mean VAS score: 2.1 ± 0.6) compared to the CHO group (3.5 ± 0.7; p < 0.01), indicating better recovery outcomes in the PRO group (Table 1).

Serum Creatine Kinase Levels:

Serum CK levels, measured as an indicator of muscle damage, showed a notable reduction in the PRO group (from 295 ± 28 U/L to 185 ± 25 U/L), while the CHO group showed a less pronounced decrease (from 300 ± 26 U/L to 260 ± 30 U/L). The between-group difference post-intervention was statistically significant (p < 0.01) (Table 1).

Strength Performance (1RM):

Improvements were observed in both 1RM bench press and squat performance in both groups. However, the PRO group exhibited greater strength gains. Bench press 1RM increased by 15.2% (from 80.5 ± 7.8 kg to 92.7 ± 8.2 kg) in the PRO group compared to 10.8% (from 79.8 ± 8.1 kg to 88.4 ± 7.9 kg) in the CHO group. Squat 1RM improved by 17.6% in the PRO group (from 105.6 ± 9.3 kg to 124.2 ± 10.1 kg) versus 12.3% in the CHO group (from 104.3 ± 8.9 kg to 117.1 ± 9.5 kg) (p < 0.05) (Table 2).

Table 1. Comparison of Muscle Soreness and CK Levels Post-Intervention

Table 2. Strength Performance (1RM) Before and After Intervention

As shown in Tables 1 and 2, the PRO group demonstrated superior improvements in both recovery and strength outcomes compared to the CHO group.

The present study demonstrated that pre-exercise protein supplementation led to significantly better muscle recovery and enhanced performance compared to carbohydrate supplementation in resistance-trained individuals. These findings align with previous research supporting the role of protein in reducing muscle damage and promoting muscle protein synthesis when consumed around exercise periods (1,2).

Protein ingestion before training has been shown to stimulate muscle protein synthesis by increasing the availability of amino acids during the exercise bout, which helps in maintaining a positive protein balance (3,4). In our study, the lower VAS scores and serum CK levels in the protein group indicate reduced muscle soreness and damage, corroborating earlier results observed by Hoffman et al. and Tipton et al. (5,6). Creatine kinase, a biomarker for muscle tissue damage, was significantly lower post-intervention in the PRO group, suggesting improved muscle integrity and repair (7).

Improved strength outcomes observed in the PRO group also reflect the anabolic benefit of protein consumed pre-exercise. Previous investigations have shown that consuming protein before resistance exercise can increase myofibrillar protein synthesis and enhance neuromuscular adaptation over time (8,9). Cribb and Hayes reported similar findings, indicating greater hypertrophy and strength development when protein supplementation was timed around resistance exercise (10).

While carbohydrate is essential for glycogen replenishment and energy provision, its sole pre-exercise consumption may not be as effective in minimizing muscle breakdown or supporting protein synthesis (11). In this study, although both groups experienced performance improvements, the magnitude of increase was greater in the protein group, supporting the idea that amino acids contribute to muscle remodeling during and after training (12).

It is important to note that the observed effects could also be influenced by the isocaloric matching of the supplements. Despite equal caloric intake, protein provided additional nitrogen sources, which may have favored anabolic processes over the purely energy-supplying role of carbohydrates (13). Moreover, the timing of ingestion (30 minutes before exercise) likely allowed optimal absorption and utilization of amino acids during exercise, further contributing to muscle protection and growth (14,15).

However, the study had limitations, including a small sample size and short duration, which may limit the generalizability of findings. Future studies should include a larger and more diverse population and assess long-term outcomes, including muscle hypertrophy and body composition changes. Additionally, examining the combined effects of carbohydrate-protein blends may offer insights into synergistic strategies for maximizing performance and recovery.

In conclusion, the findings suggest that protein supplementation prior to resistance exercise offers superior benefits in terms of muscle recovery and strength development compared to carbohydrate supplementation alone. This supports the strategic use of protein as part of pre-exercise nutrition in resistance-trained individuals.

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