Muscle soreness and rhabdomyolysis

Increasing the resting time between drop jumps lessens delayed-onset muscle soreness and limits the extent of prolonged low-frequency force depression in human knee extensor muscles

PURPOSE

Unaccustomed eccentric contractions generally result in a long-lasting contractile impairment, referred to as prolonged low-frequency force depression (PLFFD), and delayed-onset muscle soreness (DOMS). We here used repeated drop jumps (DJs) as an eccentric contraction model and studied the effects of increasing the time between DJs from 20 s to 5 min. We hypothesized that both PLFFD and DOMS would be less marked at the longer DJ interval due to the longer time to restore structural elements between DJs.

METHODS

Young men (n = 12) randomly performed 50 DJs with either 20-s (DJ-20 s) or 5-min (DJ-5 min) rest between DJs. Voluntary, 20 Hz and 100 Hz electrically stimulated isometric knee extension torques and muscle soreness were monitored before and for 7 days after DJs; serum CK activity was measured to assess muscle fibre protein leakage. In additional experiments, changes in mRNA levels were assessed in muscle biopsies collected before and 1 h after exercise.

RESULTS

A marked PLFFD was observed with both protocols and the extent of 20 Hz torque depression was smaller immediately and 1 day after DJ-5 min than after DJ-20 s (p < 0.05), whereas the MVC and 100 Hz torques were similarly decreased with the two protocols. Markedly larger differences between the two protocols were observed for the muscle soreness score, which 1-4 days after exercise was about two times larger with DJ-20 s than with DJ-5 min (p < 0.01).

CONCLUSIONS

The larger protective effect of the longer DJ interval against DOMS than against PLFFD indicates that their underlying mechanisms involve different structural elements.

Exercise-Induced Rhabdomyolysis: A Case Report and Literature Review

A 19-year-old man presented to the ED with bilateral leg pain and dark discoloration of the urine after he started an intense aerobic exercise. Blood workup showed significantly elevated creatine kinase (CK), acute kidney injury (AKI), and disseminated intravascular coagulation (DIC). The patient had a double-incision, bilateral fasciotomy with debridement to relieve the bilateral, lower-limb, compartment syndrome following admission. Also, his kidney function deteriorated, requiring several sessions of hemodialysis. His hospital stay was complicated by multidrug-resistant (MDR) Acinetobacter baumannii bacteremia. After three weeks of hospital admission, the patient was discharged home with a follow-up outpatient physiotherapy for bilateral foot drop, which showed a remarkable recovery eventually. This case highlights the potentially life-threatening risks associated with unaccustomed physical exercise and emphasizing the essential preventive measures to reduce the risk of developing exercise-induced rhabdomyolysis. We present the pathophysiology of exercise-induced rhabdomyolysis, clinical presentation, diagnosis, treatment, and prognosis.