Ketone ester supplementation blunts overreaching symptoms during endurance training overload

Abstract

Key points Overload training is required for sustained performance gain in athletes (functional overreaching). However, excess overload may result in a catabolic state which causes performance decrements for weeks (non‐functional overreaching) up to months (overtraining). Blood ketone bodies can attenuate training‐ or fasting‐induced catabolic events. Therefore, we investigated whether increasing blood ketone levels by oral ketone ester (KE) intake can protect against endurance training‐induced overreaching. We show for the first time that KE intake following exercise markedly blunts the development of physiological symptoms indicating overreaching, and at the same time significantly enhances endurance exercise performance. We provide preliminary data to indicate that growth differentiation factor 15 (GDF15) may be a relevant hormonal marker to diagnose the development of overtraining. Collectively, our data indicate that ketone ester intake is a potent nutritional strategy to prevent the development of non‐functional overreaching and to stimulate endurance exercise performance. Abstract It is well known that elevated blood ketones attenuate net muscle protein breakdown, as well as negate catabolic events, during energy deficit. Therefore, we hypothesized that oral ketones can blunt endurance training‐induced overreaching. Fit male subjects participated in two daily training sessions (3 weeks, 6 days/week) while receiving either a ketone ester (KE, n = 9) or a control drink (CON, n = 9) following each session. Sustainable training load in week 3 as well as power output in the final 30 min of a 2‐h standardized endurance session were 15% higher in KE than in CON (both P < 0.05). KE inhibited the training‐induced increase in nocturnal adrenaline (P < 0.01) and noradrenaline (P < 0.01) excretion, as well as blunted the decrease in resting (CON: −6 ± 2 bpm; KE: +2 ± 3 bpm, P < 0.05), submaximal (CON: −15 ± 3 bpm; KE: −7 ± 2 bpm, P < 0.05) and maximal (CON: −17 ± 2 bpm; KE: −10 ± 2 bpm, P < 0.01) heart rate. Energy balance during the training period spontaneously turned negative in CON (−2135 kJ/day), but not in KE (+198 kJ/day). The training consistently increased growth differentiation factor 15 (GDF15), but ∼2‐fold more in CON than in KE (P < 0.05). In addition, delta GDF15 correlated with the training‐induced drop in maximal heart rate (r = 0.60, P < 0.001) and decrease in osteocalcin (r = 0.61, P < 0.01). Other measurements such as blood ACTH, cortisol, IL‐6, leptin, ghrelin and lymphocyte count, and muscle glycogen content did not differentiate KE from CON. In conclusion, KE during strenuous endurance training attenuates the development of overreaching. We also identify GDF15 as a possible marker of overtraining.

Does ketone ester supplementation really blunt overreaching symptoms during endurance training overload?

“…In the study by Poffé et al (2019), there was no decrement in 30 min time trial performance, and 90 s sprint cycling performance was impaired to the same magnitude in both the KE and control group in response to the overload-training period, which returned to a value no different from pre-training after 3 days of recovery. From this standpoint, it could be suggested that both the KE and control group became FOR.…”

“…Poffé et al . () make elaborate remarks throughout their paper to suggest that ketone ester intake is a potent nutritional strategy that is effective in preventing the development of non‐functional overreaching (NFOR) and in preventing symptoms of overtraining. However, they make no attempt at any point in their paper to individually classify the subjects as being overreached (either functional or non‐functional) or overtrained based on their change in cycling performance and resultant recovery timeline, a classification that is typically employed in human studies (Halson et al .…”

Reply from Chiel Poffé, Monique Ramaekers, Ruud Van Thienen and Peter Hespel

“…In our recent article (Poffé et al . ) published in this journal, we demonstrated that ketone ester (KE) intake during a 3‐week endurance training overload period blunts the development of overreaching symptoms as well as enhances endurance exercise performance. The criticisms by Korevaar et al .…”

Ketone ester supplementation in endurance athletes: a miracle drink or ‘spin’?

“…As fellow scientists and endurance athletes, we read with interest the recent paper by Poffé and colleagues on ketone ester supplementation in endurance training (Poffé et al . ). The authors conclude that they demonstrated “that an oral ketone ester is a potent nutritional strategy that prevents the development of physiological overtraining symptoms and non‐functional overreaching”.…”