Nausea after Repeated Sprints: Is Lactic Acidosis Really the Culprit?

INTRODUCTION: Nausea caused by exhaustive sprinting is associated with high lactate ([La-]) and hydrogen ion concentrations ([H+]) and fall in blood pCO2, thus raising the issue of whether there is a causal link between nausea and these variables. For this reason, this study aimed to determine whether interspersing repeated sprints (RS) with periods of active, compared with passive, recovery results in lower levels of both nausea and changes in [La-], [H+], and pCO2. METHODS: Twelve male participants completed two separate sessions comprising four 30-s sprints separated by 20 min of either active (AR; cycling at 40% V˙O2peak) or passive recovery (PR). At 6 and 18 min of each recovery period, nausea was assessed via a visual analog scale (VAS), and blood samples were collected to measure [La-], [H+], and pCO2. RESULTS: RS significantly increased VAS score in both AR (P < 0.001) and PR (P < 0.01). After the first sprint, VAS was higher than preexercise in only AR (P < 0.01). AR was associated with lower VAS, [La-], [H+], and higher pCO2 (all P = 0.001) compared with PR after sprints 2-4. Linear mixed modeling indicated that each of the variables significantly predicts VAS scores (P < 0.0001). Repeated-measures correlation (rrm2) indicated that [La-] had the closest association with VAS (rrm2 = 0.22, P < 0.0001). CONCLUSION: The lower levels of both nausea and changes in [La-], [H+], and pCO2 in response to AR suggest that nausea associated with RS may be causally related with these variables. However, the absence of a close relationship between these variables after the first sprint and the findings that [La-], [H+], and pCO2 only account for 13%-22% of the variation in VAS indicate that other mechanisms may also mediate nausea.

Strength Training Improves Exercise Economy in Triathletes During a Simulated Triathlon.

PURPOSE: The completion of concurrent strength and endurance training can improve exercise economy in cyclists and runners; however, the efficacy of strength training (ST) implementation to improve economy in long-distance (LD) triathletes has not yet been investigated. The purpose of this study was to investigate physiological outcomes in LD triathletes when ST was completed concurrently to endurance training. METHODS: A total of 25 LD triathletes were randomly assigned to either 26 weeks of concurrent endurance and ST (n = 14) or endurance training only (n = 11). The ST program progressed from moderate (8-12 repetitions, ≤75% of 1-repetition maximum, weeks 0-12) to heavy loads (1-6 repetitions, ≥85% of 1-repetition maximum, weeks 14-26). Physiological and performance indicators (cycling and running economy, swim time, blood lactate, and heart rate) were measured during a simulated triathlon (1500-m swim, 60-min cycle, and 20-min run) at weeks 0, 14, and 26. Maximal strength and anthropometric measures (skinfolds and body mass) were also collected at these points. RESULTS: The endurance strength group significantly improved maximal strength measures at weeks 14 and 26 (P < .05), cycling economy from weeks 0 to 14 (P < .05), and running economy from weeks 14 to 26 (P < .05) with no change in body mass (P > .05). The endurance-only group did not significantly improve any economy measures. CONCLUSIONS: The addition of progressive load ST to LD triathletes' training programs can significantly improve running and cycling economy without an increase in body mass.

Strength Training in Long-Distance Triathletes: Barriers and Characteristics.

ABSTRACT: Luckin, KM, Badenhorst, CE, Cripps, AJ, Landers, GJ, Merrells, RJ, Bulsara, MK, and Hoyne, GF. Strength training in long-distance triathletes: Barriers and characteristics. J Strength Cond Res 35(2): 495-502, 2021-The purpose of this investigation was to identify perceived and physical barriers toward the completion of concurrent strength training and endurance training in long-distance triathletes. Three hundred ninety long-distance triathletes (224 women, 166 men; age [y]: 39 ± 10) completed a 68-question self-administered, semiquantitative survey that assessed endurance and strength training characteristics, experience in triathlon, and perceived barriers regarding the completion of strength training. Mean training hours per week was 14.92 ± 5.25, with 54.6% reporting participation in strength training. Heavy strength training was the most commonly reported (39.4%), with significantly more men completing this form of strength training (p < 0.001). Results from subjects who did not complete strength training indicated that perceived time constraints (53.1%) in addition to lack of knowledge on exercise progression and form (52.5%) are prominent perceived barriers to strength training completion. Identification of the barriers perceived by long-distance triathletes that prevent them from completing concurrent strength training and endurance training may be useful for coaches, athletes, and sports scientists who seek to incorporate strength training for injury prevention and performance improvement.

Role of lactic acidosis as a mediator of sprint-mediated nausea.

This study aims to determine whether there is a relationship between nausea level and lactic acidosis during recovery from sprinting. In all, 13 recreationally active males completed a 60 s bout of maximal intensity cycling. Prior to and for 45 min following exercise, blood pH, pCO2 , and lactate levels were measured together with nausea. In response to sprinting, nausea, lactate, and H+ concentrations increased and remained elevated for at least 10 min (p < .001), whereas pCO2 increased only transiently (p < .001) before falling below pre-exercise levels (p < .001), with all these variables returning toward pre-exercise levels during recovery. Both measures of nausea adopted for analyses (nausea profile, NP; visual analogue scale, VAS), demonstrated significant repeated measures correlation (rmcorr) post-exercise between nausea and plasma lactate (VAS and NPrrm > 0.595, p < .0001) and H+ concentrations (VAS and NPrrm > 0.689, p < .0001), but an inconsistent relationship with pCO2 (VAS rrm  = 0.250, p = .040; NP rrm  = 0.144, p = .248) and bicarbonate levels (VAS rrm  = -0.252, p = .095; NP rrm  = -0.397, p = .008). Linear mixed modeling was used to predict the trajectory of nausea over time, with both lactate and H+ concentrations found to be key predictors of nausea (p < .0001). In conclusion, this study reveals a strong positive relationship between nausea and both H+ and lactate concentrations during recovery from sprinting, a finding consistent with H+ and lactate being potential mediators of nausea post-sprinting. However, as the timing of the recovery of both H+ and lactate was delayed, compared to that of nausea, further research is required to confirm these findings and investigate other potential mechanisms.