Ischemic preconditioning (IPC) has been repeatedly reported to augment maximal exercise performance over a range of exercise durations and modalities. However, an examination of the relevant literature indicates that the reproducibility and robustness of ergogenic responses to this technique are variable, confounding expectations about the magnitude of its effects. Considerable variability among study methodologies may contribute to the equivocal responses to IPC. This review focuses on the wide range of methodologies used in IPC research, and how such variability likely confounds interpretation of the interactions of IPC and exercise. Several avenues are recommended to improve IPC methodological consistency, which should facilitate a future consensus about optimizing the IPC protocol, including due consideration of factors such as: location of the stimulus, the time between treatment and exercise, individualized tourniquet pressures and standardized tourniquet physical characteristics, and the incorporation of proper placebo treatments into future study designs.

Ischemic preconditioning (IPC) has been reported to augment exercise performance, but there is considerable heterogeneity in the magnitude and frequency of performance improvements. Despite a burgeoning interest in IPC as an ergogenic aid, much is still unknown about the physiological mechanisms that mediate the observed performance enhancing effects. This narrative review collates those physiological responses to IPC reported in the IPC literature and discusses how these responses may contribute to the ergogenic effects of IPC. Specifically, this review discusses documented central and peripheral cardiovascular responses, as well as selected metabolic, neurological, and perceptual effects of IPC that have been reported in the literature.

Psychiatric and metabolic disorders are highly comorbid and the relationship between these disorders is bidirectional. The mechanisms underlying the association between psychiatric and metabolic disorders are presently unclear, which warrants investigation into the dynamics of the interplay between metabolism, substrate utilization, and energy expenditure in psychiatric populations, and how these constructs compare to those in healthy controls. Indirect calorimetry (IC) methods are a reliable, minimally invasive means for assessing metabolic rate and substrate utilization in humans. This review synthesizes the extant literature on the use of IC on resting metabolism in psychiatric populations to investigate the interaction between psychiatric and metabolic functioning. Consistently, resting energy expenditures and/or substrate utilization values were significantly different between psychiatric and healthy populations in the studies contained in this review. Furthermore, resting energy expenditure values were systematically overestimated when derived from predictive equations, compared to when measured by IC, in psychiatric populations. High heterogeneity between study populations (e.g., differing diagnoses and drug regimens) and methodologies (e.g., differing posture, time of day, and fasting status at measurement) impeded the synthesis of results. Standardized IC protocols would benefit this line of research by enabling meta-analyses, revealing trends within and between different psychiatric disorders.

Ischemic preconditioning (IPC) is a potential ergogenic technique but the response rates vary considerably in the literature. The use of markedly different IPC protocols among the published literature, including pressure, rounds of ischemia, and time latencies potentially contribute to heterogenous responses. This study investigated whether the duration of time between the application of IPC and the commencement of exercise may explain equivocal ergogenic results. Fourteen (n = 11 male, n = 3 female) moderately trained volunteers participated in a familiarization and three experimental trials: no IPC (CON), IPC-5 (4 × 5 min IPC applied 5 min before exercise), and IPC-30 (4 × 5 min IPC applied 30 min before exercise). Participants completed maximal 10-min accumulated work (kJ) cycling time trials. Oxygen uptake (V.O2), heart rate, vastus lateralis tissue oxygenation, and blood lactate concentrations ([La^-]_b) were measured before, during, and after exercise. There were no differences in performance or physiological responses during or after exercise among CON, IPC-5, and IPC-30. These findings add further evidence to the existing literature reporting that IPC-related ergogenicity is equivocal when administered 5 or 30 min before exercise. These results reinforce the requirement to clarify whether there exists an IPC protocol that reliably elicits an ergogenic effect.