Programmed vs. Thirst-Driven Drinking during Prolonged Cycling in a Warm Environment

We compared the effect of programmed (PFI) and thirst-driven (TDFI) fluid intake on prolonged cycling performance and exercise associated muscle cramps (EAMC). Eight male endurance athletes (26 ± 6 years) completed two trials consisting of 5 h of cycling at 61% V˙O2peak followed by a 20 km time-trial (TT) in a randomized crossover sequence at 30 °C, 35% relative humidity. EAMC was assessed after the TT with maximal voluntary isometric contractions of the shortened right plantar flexors. Water intake was either programmed to limit body mass loss to 1% (PFI) or consumed based on perceived thirst (TDFI). Body mass loss reached 1.5 ± 1.0% for PFI and 2.5 ± 0.9% for TDFI (p = 0.10). Power output during the 20 km TT was higher (p < 0.05) for PFI (278 ± 41 W) than TDFI (263 ± 39 W), but the total performance time, including the breaks to urinate, was similar (p = 0.48) between conditions. The prevalence of EAMC of the plantar flexors was similar between the drinking conditions. Cyclists competing in the heat for over 5 h may benefit from PFI aiming to limit body mass loss to <2% when a high intensity effort is required in the later phase of the race and when time lost for urination is not a consideration.

Exercise-associated Muscle Cramps in Runners: A Review

Objective: Exercise-associated Muscle Cramp (EAMC) is an intense, painful, and involuntary contraction of skeletal muscles during a physical activity. Runners are more prone to this syndrome than other athletes. The present paper aims to review of the literature on EAMC in runners to determine the reasons and nature of EAMC in this sports field. Methods: A search was conducted for related studies from 1997 to 2021 in MEDLINE/PubMed, EMBASE/SCOPUS, LILACS, CINAHL, CENTRAL, Web of Science, PEDro, Google Scholar as well as MagIran, IranDoc, IranMedex, MedLib using MeSH Keywords. The reference section of the studies were also checked to find more studies. Finally, 15 eligible papers on EAMC in runners were reviewed and findings were reported. Results: Several factors were found to be effective in EAMC among runners, including dehydration, electrolyte deficit, cold, long training or competition period, increased body temperature during training or competition, history of injury or muscle cramp, increased training intensity in short time, and dietary restrictions. Conclusion: The cause of EAMC in runners seems to be multifactorial.

An Evidence-Based Review of the Pathophysiology, Treatment, and Prevention of Exercise Associated Muscle Cramps

ABSTRACT Exercise-associated muscle cramps (EAMC) are common and frustrating for athletes and the physically active. We critically-appraised the EAMC literature to provide evidence-based treatment and prevention recommendations. While the pathophysiology of EAMC appears controversial, recent evidence suggests EAMC are due to a confluence of unique intrinsic and extrinsic factors rather than a singular etiology. The treatment of acute EAMC continues to include self-application or clinician-guided gentle static stretching until EAMC abatement. Once the painful EAMC are alleviated, clinicians can continue treatment on the sidelines by focusing on patient-specific risk factors that the clinician believes may have contributed to the genesis of EAMC. For EAMC prevention, clinicians should first perform a thorough medical history followed by identification of the patients' unique risk factors that could have coalesced to elicit EAMC. Individualizing EAMC prevention strategies will likely be more effective than generalized advice (e.g., drink more fluids).

Exertional Rhabdomyolysis Following Noncontact Collegiate Recreational Activity: A Case Report

A healthy 19-year-old male (body mass = 68.04 kg, height = 175.26 cm) participating in a collegiate intramural flag football tournament presented with unilateral gastrocnemius exercise-associated muscle cramps. He was given electrolytes, stretched, and returned to play. The exercise-associated muscle cramps progressed to his quadriceps bilaterally within 23 min of initial reported symptoms. Emergency medical services was activated and the patient was transported by ambulance to the emergency department, where he was diagnosed with acute exertional rhabdomyolysis. This case report explores the rarity of exertional rhabdomyolysis in a noncontact intramural sport and highlights the necessity for early recognition and treatment.

Acute Passive Static Stretching and Cramp Threshold Frequency

Context: Exercise-associated muscle cramps are a common clinical problem for athletes. Objective: To determine whether acute passive static stretching altered cramp threshold frequency (CTF) of electrically induced muscle cramps. Design: Crossover study. Setting: Laboratory. Patients or Other Participants: Seventeen healthy college-aged individuals. Intervention(s): Stretching or no stretching. Main Outcome Measure(s): The independent variable was the static stretch versus the no-stretch condition, and the dependent variable was the CTF. Results: The CTF increased in both the control (pretest: 18.12 ± 6.46 Hz, posttest: 19.65 ± 7.25 Hz; P = .033) and stretching (pretest: 18.94 ± 5.96 Hz, posttest: 20.47 ± 7.12 Hz; P = .049) groups. No difference between the groups was found (t15 = 0.035, P = .97). Conclusions: Acute passive static stretching did not seem to increase the CTF.