The effect of almond consumption on elements of endurance exercise performance in trained athletes

Abstract

Background

Almonds are a healthy tree nut food with high nutrient density. Their consumption has been shown to ameliorate oxidative stress, inflammation, etc. The objective of the study was to examine the effect of almonds on elements of endurance exercise performance in trained athletes.

Methods

A 10-week crossover, placebo controlled study was conducted. Eight trained male cyclists and two triathletes were randomly assigned to consume 75 g/d whole almonds (ALM) or isocaloric cookies (COK) with equal subject number. They consumed the assigned food for 4 wks and then the alternate food for another 4 wks. They underwent 3 performance tests including 125-min steady status exercise (SS) and 20-min time trial (TT) on an indoor stationary trainer at the start of the study (BL) and at the end of each intervention phase. Venous blood was collected in the morning prior to the performance test for biochemical measurements and finger blood during the test for glucose determination. Carbohydrate and fat oxidation, energy expenditure, and oxygen use were calculated using respiratory gas analysis.

Results

ALM increased cycling distance during TT by 1.7 km as compared BL (21.9 vs. 20.2 km, P = 0.053) and COK increased 0.6 km (20.8 vs. 20.2 km, P > 0.05). ALM, but not COK, led to higher CHO and lower fat oxidation and less oxygen consumption during TT than BL (P < 0.05), whereas there was no significant difference in heart rate among BL, ALM and COK. ALM maintained higher blood glucose level after TT than COK (P < 0.05). ALM had higher vitamin E and haemoglobin and lower serum free fatty acid (P < 0.05), slightly elevated serum arginine and nitric oxide and plasma insulin (P > 0.05) than BL, and a higher total antioxidant capacity than COK (P < 0.05).

Conclusions

Whole almonds improved cycling distance and the elements related to endurance performance more than isocaloric cookies in trained athletes as some nutrients in almonds may contribute to CHO reservation and utilization and effective oxygen utilization. The results suggest that almonds can be incorporated into diets of those who undertake exercise training for performance improvement.

Keywords:

• Almonds
• Exercise performance
• Substrate oxidation
• Antioxidant defense capacity

Electronic supplementary material

The online version of this article (doi:10.1186/1550-2783-11-18) contains supplementary material, which is available to authorized users.

Electronic supplementary material

The online version of this article (doi:10.1186/1550-2783-11-18) contains supplementary material, which is available to authorized users.

Acknowledgements

The study was supported by the Almond Board of California. The authors thank the coaches and physicians for the Chinese Bayi Cycling and Triathlon Team for their support on training and performance test arrangement and dietary information collection.

Competing interests

The authors declare that they have no competing interest and that the results of the present study do not constitute endorsement by JISSN.

Authors’ contributions

MY and LZ were responsible for study design, data collection, statistical analysis, and manuscript preparation. JF, HG, CF, QW, JS, BX, and JL were responsible for biochemical work, dietary record and calculation, data collection/entry, and assistance with manuscript preparation. GH and KL participated in formulating study design. JB and COC helped draft the manuscript. All authors read and approved the final manuscript.