New Research Casts Doubt on Efficacy of Low-Carb and Fasted Training Approaches

A five-week study published in the journal Nutrients compared two carbohydrate (CHO) strategies for well-trained cyclists: periodized intake based on training intensity vs. a high-CHO diet. Both groups improved endurance (measured by MLSS), gained muscle, and lost fat. However, the periodized CHO strategy offered no performance or metabolic advantages. This suggests that, for short-term training, a high-CHO diet may be equally effective for well-trained cyclists, while further research is needed to explore long-term effects and tailor CHO manipulation to specific training goals.

Key Points

This study investigated whether a cycling-specific strategy of varying carbohydrate (CHO) intake based on training workload ("periodized CHO") offers any advantage over a standard high-CHO diet for well-trained cyclists.

Participants: 17 trained cyclists with high peak oxygen uptake (VO2peak) were divided into two groups:

• Periodized CHO (PCHO): 13 training sessions with low CHO availability.

• High-Carbohydrate (HCHO): All sessions followed high pre-exercise glycogen levels.

Training and Outcomes:

• Both groups followed the same five-week training program.

• Both showed increases in maximal lactate steady state (MLSS) (measure of endurance training adaptation) but no improvement in time to exhaustion at MLSS intensity.

• Both groups increased muscle mass and decreased body fat.

• No significant differences were observed in:

  • Carbohydrate or lipid oxidation (fuel sources)

  • Heart rate

  • Post-exercise lactate concentration

Key Takeaways:

• Periodizing CHO intake for five weeks did not offer performance or metabolic advantages over a high-CHO diet in well-trained cyclists.

• Both approaches led to positive training adaptations and body composition changes.

• This study adds to the mixed evidence on CHO periodization, suggesting it may not be a universally beneficial strategy for endurance athletes.

Further Research:

• Longer-term studies with additional performance measures.

• Exploring CHO periodization effects on different athlete levels and training programs.

• Investigating the potential benefits of CHO manipulation for specific training goals.

In the realm of endurance sports, the strategic manipulation of carbohydrate intake, known as carbohydrate periodization, has been a topic of considerable interest. This nutritional strategy is often employed with the aim of enhancing athletic performance, particularly in sports where endurance is key. The present study delves into this topic, offering valuable insights into the effectiveness of periodized carbohydrate diets compared to traditional high-carbohydrate diets.

Comparative Analysis of Traditional and Periodized Carbohydrate Diets

The study observed two groups of athletes, one following a periodized carbohydrate diet and the other adhering to a traditional high-carbohydrate diet. Both groups showed improvements in maximal lactate steady state (MLSS) tests, expressed in watts and watts/kg. However, the periodized carbohydrate diet did not demonstrate a superior impact in time-to-exhaustion tests as compared to the high-carbohydrate diet.

Substrate Utilization and Metabolism: Key Observations

In evaluating carbohydrate (CHO) and lipid (LIP) oxidation and respiratory exchange ratio (RER) during the time-to-exhaustion test at MLSS intensity, the study found no significant differences pre- and post-intervention. This indicates that the type of diet, whether periodized in carbohydrates or high in carbohydrates, does not significantly alter substrate utilization during intense endurance exercises.

Physiological and Anthropometric Changes: Diet and Training Effects

Significant improvements in muscle mass and reductions in fat percentage were noted in participants from both diet groups. This suggests that controlled caloric intake and structured training play a crucial role in enhancing body composition, irrespective of the dietary approach followed.

Carbohydrate Periodization: Relevance and Limitations in Endurance Sports

While some studies have highlighted the benefits of carbohydrate periodization strategies like “fasted training” or “sleep-low” in enhancing endurance performance, a comprehensive review and meta-analysis suggest that these benefits might not be as pronounced as previously thought. The present study contributes to this body of research, underscoring the need for further investigation into the specific cellular responses to different nutritional interventions in athletes.

Conclusions: Understanding the Role of Diet in Endurance Training

The findings of this study indicate that periodizing carbohydrate intake does not significantly influence MLSS or change substrate oxidation during a time-to-exhaustion test at MLSS intensity. Both high-carbohydrate and periodized carbohydrate diets were effective in improving anthropometric parameters and exercise performance when caloric intake and training were carefully controlled.

Practical Applications: Tailoring Nutrition to Endurance Sports

When planning diets for endurance athletes, it is crucial to consider the specific demands of the sport and the individual needs of the athlete. High-carbohydrate diets remain prevalent in endurance sports, where high glycogen stores are critical. It is essential to maintain adequate energy availability to avoid adverse effects that could compromise sports performance and health.

Reference Article

Vyas, C. M., Manson, J. E., Sesso, H. D., Cook, N. R., Rist, P. M., Weinberg, A., Moorthy, M. V., Baker, L. D., Espeland, M. A., Yeung, L., Brickman, A. M., & Okereke, O. I. (2024, January 1). Effect of multivitamin-mineral supplementation versus placebo on cognitive function: results from the clinic subcohort of the COcoa Supplement and Multivitamin Outcomes Study (COSMOS) randomized clinical trial and meta-analysis of 3 cognitive studies within COSMOS. The American Journal of Clinical Nutrition. https://doi.org/10.1016/j.ajcnut.2023.12.011

Related

https://healthnewstrend.com/carbohydrates-their-impact-on-health-and-disease

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