Elite athletes have temporary mitochondrial impairment following intense workouts, according to new research, which suggests they may need to be mindful about overtraining.
Mitochondria are organelles that are responsible for most of the useful energy derived from the breakdown of carbohydrates and fatty acids, which is converted to ATP by the process of oxidative phosphorylation. Mitochondrial capacity is a term used to describe the body’s ability to generate energy, and is one factor associated with increased athletic performance during endurance exercise. Previous research found that untrained recreational athletes had a decrease in mitochondrial capacity after sprinting exercises.
In this study, the researchers worked with a small group of male elite athletes, many of whom were national title holders or had international recognition for their performance in cycling and triathlon. The athletes participated in a four-week training programme in their primary sport, which consisted of two to four days of low-to-moderate–intensity endurance workouts, followed by three days of more intense training. These intense workouts included high-intensity interval training in the morning, followed by a seven-hour break and then a moderate-intensity cycling session in the afternoon. Each volunteer did between 12 and 20 hours of activity per week. The athletes, though used to heavy training, were not accustomed to this specific workout schedule.
The researchers were surprised to observe that the highly trained participants’ mitochondrial capacity was impaired after the month-long training period. “We thought that elite athletes should be more resistant against [these] kind of alterations,” said Filip Larsen, PhD, of the Swedish School of Sport and Health Sciences and corresponding author of the study.
However, elite athletes may be able to prevent temporary mitochondrial impairment by listening to their bodies, the researchers suggested. By paying attention to changes such as “mood disturbances, reductions in maximal heart rate [during exercise] and muscles that feel heavy and unresponsive” top athletes may be able to pull back and avoid overtraining situations that could contribute to reduced mitochondrial content and function, Larsen explained. “Exercise is good for you, but too much unaccustomed training might have mitochondrial consequences.”
The study also found that reduced mitochondrial capacity did not affect exercise performance, suggesting that oxygen delivery from the heart to the muscles plays a more important role than mitochondrial function in performance. Expression of three proteins with strong antioxidant properties were also found to be increased in the muscles after intense training.
Source: American Physiological Society
Journal information: Daniele A. Cardinale et al, Short term intensified training temporarily impairs mitochondrial respiratory capacity in elite endurance athletes, Journal of Applied Physiology (2021). DOI: 10.1152/japplphysiol.00829.2020
