How Much Does Weight Training Deplete Glycogen Stores?
Meta-analysis reveals training volume and duration drive depletion more than load intensity, with implications for performance and lifters training multiple times daily.
A new systematic review and meta-analysis has found that a single resistance training session significantly depletes glycogen stores in the vastus lateralis muscle (part of the quadriceps) by an average of 104.3 mmol/kg of dry mass, representing approximately 21% of pre-training levels. However, the study reveals that this depletion varies considerably depending on training volume, intensity, session duration, and training status. More sets and longer sessions led to greater glycogen depletion, whereas higher-intensity loads actually resulted in less depletion due to reduced total work capacity. Untrained lifters also experienced greater depletion than their trained counterparts, suggesting that training adaptations may improve glycogen preservation during resistance exercise. While typical training sessions do not deplete glycogen to levels that impair performance (below 280-300 mmol/kg dry weight), the findings highlight important considerations for lifters who train multiple times per day or follow low-carbohydrate approaches.
Aim
The research team conducted this systematic review and meta-analysis to quantify how much glycogen a single resistance training session depletes and to identify which training variables influence the extent of this depletion. While endurance exercise and glycogen metabolism have been extensively studied, the factors influencing muscle glycogen depletion during resistance exercise have been less well understood. The authors aimed to provide evidence-based insights that could inform carbohydrate intake recommendations for strength athletes, bodybuilders, and those engaging in resistance training programs.
Methods
Researchers conducted a systematic search across PubMed, Web of Science, and Scopus databases from inception until July 28, 2024, following PRISMA guidelines. They included studies that measured muscle glycogen concentration via needle biopsy before and after resistance exercise in healthy adults aged 18 years or older. Studies were excluded if they administered dietary constituents apart from water during training or if any other exercise occurred before the resistance session.
The final analysis included 20 studies comprising 180 participants (168 men and 12 women). The average age across studies was 25.6 years, ranging from 19.6 to 53.3 years. Training protocols varied widely: session duration averaged 33 minutes (ranging from 7 to 120 minutes), sets per session averaged 8.7 (ranging from 3 to 20 sets), rest intervals between sets averaged 127.5 seconds (ranging from 30 to 180 seconds), and training intensity averaged 72.3% of one-repetition maximum (ranging from 35% to 85% of 1RM).
All studies measured glycogen concentration in the vastus lateralis muscle through muscle biopsies. Pre-exercise glycogen concentration averaged 528.3 mmol/kg of dry mass, while post-exercise levels dropped to 404.4 mmol/kg of dry mass. The researchers used a multilevel, random-effects meta-analysis to calculate the overall mean difference with 95% confidence intervals and conducted meta-regression analyses to examine how continuous variables (like number of sets, session duration, and intensity) influenced glycogen depletion.
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Results
The meta-analysis revealed a significant decrease in muscle glycogen following resistance training, with an average depletion of 104.3 mmol/kg dry mass (95% CI: 137.6 to 71.0). This represents approximately a 21% reduction from pre-training levels.
Meta-regression analysis identified several key moderating factors. The number of sets had a significant relationship with glycogen depletion: each additional set resulted in an estimated 11.2 mmol/kg greater depletion (95% CI: 18.0 to 4.3). Session duration also showed a positive relationship, with longer sessions causing more depletion (estimate: 1.3 mmol/kg per minute, 95% CI: 2.3 to 0.3).
Surprisingly, higher training intensity was associated with less glycogen depletion (estimate: 2.88 mmol/kg per 1% increase in intensity, 95% CI: 1.2 to 4.5). The authors suggest this counterintuitive finding relates to the lower total volume of work that can be performed with heavier loads.
Subgroup analysis revealed that varied intensity protocols (where load changed across sets) resulted in significantly greater glycogen depletion (162.9 mmol/kg) compared to fixed intensity protocols (82.5 mmol/kg). However, this difference appeared largely driven by the fact that varied intensity studies used substantially higher training volumes, averaging approximately 13.5 sets compared to 7.5 sets in fixed intensity studies.
Training status also influenced glycogen utilization. Untrained participants experienced greater depletion (113.0 mmol/kg) compared to trained participants (101.3 mmol/kg). The researchers propose this may reflect improved oxidative capacity and more efficient neuromuscular coordination in trained lifters, reducing unnecessary energy expenditure.
Notably, the study found no significant effects of rest interval duration between sets or participant age on glycogen depletion.
One important finding relates to fiber type-specific depletion. While the meta-analysis examined whole-muscle glycogen, one included study (Hokken et al., 2021) found that 48% of type II muscle fibers showed near-depleted levels of intramyofibrillar glycogen after resistance exercise, even though whole-muscle measurements appeared more modest. This suggests that average muscle glycogen measurements may not reflect the substantial depletion occurring in specific fiber types and subcellular compartments.
Practical Takeaways
For lifters training once per day with typical volumes and loads, this research suggests that resistance training causes moderate glycogen depletion that likely does not impair performance, as post-exercise levels typically remain above the critical threshold of 280-300 mmol/kg dry mass where muscle contraction becomes impaired. However, several practical considerations emerge from these findings:
Training volume and duration matter more than intensity for glycogen depletion. If you are doing higher volumes (more sets) or longer training sessions, you will deplete more glycogen. If glycogen preservation is a priority (such as when training multiple times per day), consider moderating total sets and session length rather than focusing primarily on load intensity.
Higher intensity training with fewer sets may preserve glycogen better. While heavier loads are often assumed to be more metabolically demanding, the reduced total work volume means less glycogen depletion. This could be relevant for powerlifters or those training with lower repetition ranges.
Trained lifters appear more glycogen-efficient. The finding that trained participants depleted less glycogen suggests that training adaptations may improve metabolic efficiency and reduce carbohydrate reliance during resistance exercise. Newer lifters may need to pay closer attention to carbohydrate intake, particularly around training sessions.
Multiple daily training sessions require attention to carbohydrate intake. While a single training session typically does not deplete glycogen to performance-limiting levels, those training multiple times within 24 hours should prioritise post-training carbohydrate intake to support subsequent performance. The research team notes that low glycogen levels can impair force production, increase fatigue, and hinder recovery.
Low-carbohydrate approaches may impact high-volume training. Athletes following low-carbohydrate or ketogenic diets should be aware that high-volume resistance training programs (many sets, long durations) may be more challenging to sustain without adequate glycogen stores. While some adaptation occurs, carbohydrate periodisation (strategically timing carbohydrate intake around training demands) may be warranted.
Individual muscle fibers may be more depleted than whole-muscle measurements suggest. The finding that nearly half of type II fibers showed near-complete intramyofibrillar glycogen depletion despite modest whole-muscle changes highlights that performance impacts may occur even when average glycogen levels appear adequate. Type II fibers are critical for strength and power production, making this particularly relevant for resistance training.
Wrapping Up
This comprehensive meta-analysis provides the first quantitative synthesis of how resistance training affects muscle glycogen stores, revealing an average 21% depletion per session that is heavily influenced by training volume, duration, and training status. While typical training sessions are unlikely to deplete glycogen to performance-limiting levels, the findings underscore the importance of considering training variables and carbohydrate intake strategies, particularly for lifters training multiple times per day or following restrictive carbohydrate approaches. The research also highlights important gaps in our understanding, including the need for more studies examining female lifters, different muscle groups beyond the quadriceps, and fiber type-specific glycogen depletion patterns.
Reference
Hamidvand, A., Delleli, S., Rothschild, J. A., Chenaghchi, F., Jafari, A., & Naderi, A. (2025). Acute effects of resistance exercise on skeletal muscle glycogen depletion: A systematic review and meta-analysis. Physiological Reports, 13(24), e70683. https://doi.org/10.14814/phy2.70683
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