I'm directing readers to three papers in this month's journal. First, exogenous ketones are currently one of the most talked about sports supplements, having gained notoriety for their apparent use by multiple elite cycling teams at this year's Tour de France. However, there have been only a handful of peer-reviewed studies on their ergogenic potential. Evans et al. investigated whether the addition of a ketone monoester supplement to an optimal carbohydrate fueling strategy for endurance athletes has any impact on performance in a 10-km treadmill-based time-trial. Despite elevating circulating ketone body concentrations into the ~1.5 mM range, there were negligible effects on either the metabolic response to submaximal exercise or 10-km running performance compared to carbohydrate alone. While exogenous ketones are the subject of much interest, these are early days and the jury remains out on whether these supplements can justify the hype.
Next, Troschel and colleagues investigated the feasibility of high-intensity exercise in a patient diagnosed with glioblastoma multiforme (GBM). Currently, exercise is largely discouraged in GBM patients as caregivers fear seizures or falls. In this current study, the 33-year-old patient underwent an individualized, physically demanding training program despite multiple surgery and radiochemotherapy regimens, and disease progression. The patient's fitness improved significantly as evidenced by increasing fitness parameters, enabling him to complete two marathon runs. The program was continued for nearly two years and only stopped six weeks before the patient passed away. During the entire study program, no adverse events were encountered despite long-time high-intensity exercise and continuous GBM treatment. Overall, these results highlight that even demanding exercise is possible in GBM patients and physical activity should not generally be discouraged.
Finally, Kouvelioti et al. examined the relationship between exercise-induced changes in inflammatory cytokines and those of sclerostin following high-intensity interval exercise in young adults, and whether this relationship was different between high-impact and no-impact exercise. Sclerostin is a key osteokine that downregulates bone formation. Using a cross-over design, 38 females and males performed two high-intensity interval exercise trials, running and cycling, with blood collected pre-exercise, and several times post-exercise. Both pro-inflammatory (IL-1β, IL-6, TNF-α) and anti-inflammatory (IL-10) cytokines, and sclerostin increased post-exercise with minimal differences only in the timing of these responses between running and cycling. The exercise-induced increase in sclerostin was significantly correlated with the corresponding changes in inflammatory cytokines, specifically TNF-α, independent of the impact. Overall, these results highlight the potential role of inflammation in post-exercise bone homeostasis in humans.
L. Bruce Gladden
School of Kinesiology