Injury epidemiology in competing and non-competing spanish crossfit® practitioners / Epidemiología lesional en practicantes de crossfit® competidores y no competidores españoles

La falta de estudios sobre lesiones en Crossfit® en España, motiva la realización de este estudio epidemiológico descriptivo, observacional y retrospectivo, analizando la incidencia y las características de las lesiones sufridas por practicantes de Crossfit® competidores y no competidores. Se registraron las lesiones sufridas por 434 deportistas entre el 1 de enero y el 31 de diciembre de 2019. Se registraron datos sobre el número de lesiones, lesiones más frecuentes, distribución, tipo, ubicación, el momento en que ocurrieron y la causa de las lesiones que afectan el sistema musculoesquelético. La tasa de lesiones en esta población fue de 3,48 lesiones por 1000 horas de exposición al riesgo. El hombro y la zona lumbar fueron las zonas anatómicas más frecuentemente lesionadas, siendo el musculo y el tendón el tejido de asiento más habitual de las lesiones. El Powerlifting fue la actividad más lesiva. (AU)

The lack of studies on Crossfit® injuries in Spain, motivates the realization of this descriptive, observational and retrospective epidemiological study, analyzing the incidence and characteristics of injuries suffered by Crossfit® competitors and non-competitors.The injuries suffered by 434 athletes between from January 1st to December 31st 2019 were recorded. We collected data on the number of injuries, the most frequent injuries, their distribution, type, location, the moment at which these occurred and the cause of the injuries affecting the musculoeskeletal system. We found that the injury rate in this population was 3,48 injuries per 1000 hours of risk. The shoulder and lumbar area were the most frequently injured anatomical areas, with muscle and tendon being the most common seat tissue of injuries. Powerlifting was the most damaging activity. (AU)

Comparison of different field tests to assess the physical capacity of post-COVID-19 patients.

BACKGROUND: In coronavirus disease (COVID-19), physical capacity is one of the most impaired sequelae. Due to their simplicity and low cost, field tests such as the six-minute walk test (6MWT) are widely used However, in many places it is difficult to perform them and alternatives can be used such as the 1 min sit-to-stand test (1min-STST) or the Chester step test (CST). Therefore, our objective was to compare the 6MWT, 1min-STST and the CST in post-COVID-19 patients. METHODS: We conducted a cross-sectional analysis in post-COVID-19 patients, compared with matched controls (CG). Demographic characteristics and comorbidities were collected. We analysed oxygen saturation (SpO2), heart rate (HR), and the modified Borg scale in the 6MWT, 1min-STST, and CST. Additionally, the correlations between tests were analysed. RESULTS: We recruited 27 post-COVID-19 patients and 27 matched controls. The median age was 48 (IQR 43-59) years old (44% female). The median distance walked in 6MWT was 461 (IQR 415-506) m in post-COVID-patients and 517 (IQR 461-560) m in CG (p = 0.001). In 1min-STST, the repetitions were 21.9 ± 6.7 and 28.3 ± 7.1 in the post-COVID-19 group and CG, respectively (p = 0.001). In the CST, the post-COVID-19 group performed 150 (86-204) steps vs the CG with 250 (250-250) steps (p < 0.001). We found correlations between the 6MWT with the 1min-STST in COVID-19 patients (r = 0.681, p < 0.001) and CG (r = 0.668, p < 0.001), and between the 6MWT and the CST in COVID-19 patients (r = 0.692, p < 0.001). CONCLUSION: The 1min-STST and the CST correlated significantly with the 6MWT in patients post-COVID-19 being alternatives if the 6MWT cannot be performed.

Understanding the meaning of lactate threshold in resistance exercises.

This study compares acute cardiorespiratory, metabolic, mechanical and rating of perceived effort (RPE) responses to 2 different prolonged constant-load exercises, half-squat (HS) and cycle ergometry, performed at a workload corresponding to the lactate threshold (LT). A total of 18 healthy subjects completed 5 exercise tests separated by 48 h rest periods: an incremental cycle ergometer test, a constant-load cycle ergometer test at LT intensity, a one-repetition maximum (1RM) HS test, an incremental HS test and a constant-load HS test at LT intensity. In both constant-load tests, cardiorespiratory, metabolic and RPE data were recorded. Mechanical responses before and after each test were assessed in terms of jump height and mean power measured in a counter movement jump (CMJ) test. In both exercises, cardiorespiratory and metabolic responses stabilized, though cardiorespiratory responses were significantly greater for cycle ergometry (P<0.001), with the exception of respiratory exchange ratio (RER), which was higher for HS (P=0.028). Mechanical fatigue was observed in only HS (P<0.001). In conclusion, different exercise modalities induced different yet stable acute cardiorespiratory and metabolic responses. Although such responses were significantly reduced in HS, greater mechanical fatigue was produced, most likely because of the particular muscle actions involved in this form of exercise.

AMPD1 genotypes and exercise capacity in McArdle patients.

The purpose of this study was to assess if there exists an association between C34T muscle adenosine monophosphate deaminase ( AMPD1) genotypes (i.e., normal homyzygotes [CC] vs. heterozygotes [ CT]) and directly measured indices of exercise capacity (peak oxygen uptake [VO(2peak)], ventilatory threshold [VT], gross mechanical efficiency [GE], etc.) in 44 Caucasian McArdle patients (23 males, 21 females). All patients performed a graded cycle ergometer test until exhaustion (for VO(2peak) and VT determination) and a 12-min constant-load test at the power output eliciting the VT (for GE determination). We found no significant difference in indices of exercise capacity between CC (n = 18) and CT genotypes (n = 5) in the group of male patients (p > 0.05). In contrast, the VO(2) at the VT was significantly lower (p < 0.05) in CT (n = 4; 7.9 +/- 0.4 ml/kg/min) than in CC female patients (n = 17; 11.0 +/- 0.9 ml/kg/min). In summary, heterozigosity for the C34T allele of the AMPD gene is associated with reduced submaximal aerobic capacity in female patients with McArdle disease and might partly account, in this gender, for the variability that exists in the phenotypic manifestation of the disease.

The I allele of the ACE gene is associated with improved exercise capacity in women with McArdle disease.

BACKGROUND: McArdle disease is an uncommon metabolic disorder usually characterized by marked exercise intolerance although great individual variability exists in its phenotypic manifestation. OBJECTIVE: The purpose of this study was to determine the association between angiotensin-converting enzyme (ACE) genotypes and indices of exercise capacity (peak oxygen uptake (VO(2)peak), ventilatory threshold (VT) and gross mechanical efficiency (GE)) in patients with McArdle disease. Based on previous research, it was hypothesized that the I allele might favourably influence exercise capacity. METHODS: Forty-four Spanish patients (23 males, 21 females) and 44 age-matched and gender-matched controls (23 males, 21 females) performed a graded cycle-ergometer test until exhaustion (for VO(2)peak and VT determination) and a 12 min constant-load test at the power output eliciting the VT (for GE determination). RESULTS: No significant difference (p>0.05) was found in indices of exercise capacity between ID + II genotypes and DD homozygotes in the group of male patients, male controls and female controls. However, in the group of female patients, the ID + II group (n = 11) had a higher VO(2)peak than DD homozygotes (n = 10) (15.8 (SEM 1.6) ml/kg/min versus 11.9 (SEM 0.9) ml/kg/min, respectively; p<0.05). CONCLUSIONS: The I allele of the ACE gene is associated with a higher functional capacity in female patients, and might partly explain the individual variability in the phenotypic manifestation of McArdle disease.

Functional capacity of children with leukemia.

The purpose of this study was to determine if the functional capacity and quality of life of children receiving treatment against acute lymphoblastic leukemia (ALL) is decreased compared to healthy age and gender-matched children. Functional capacity was assessed with a number of measurements as the peak oxygen uptake (VO2peak) and ventilatory threshold determined during a ramp treadmill test, functional mobility (Timed Up and Down Stairs test [TUDS]) and ankle dorsiflexion passive and active range of motion (passive and active DF-ROM, respectively). Quality of life (QOL) was determined with the Spanish version of the Child Report Form of the Child Health and Illness Profile-Child Edition (CHIP-CE/CRF). Fifteen children (9 boys, 6 girls; mean [SD] age: 6.8 +/- 3.1 years) receiving maintenance therapy against ALL were studied and fifteen, nonathletic healthy children (9 boys, 6 girls; 6.9 +/- 3.3 years) were selected as controls. The mean values of VO2peak and active DF-ROM were significantly (p < 0.05) lower in patients (25.3 +/- 6.5 ml . kg (-1) . min (-1) vs. 31.9 +/- 6.8 ml . kg (-1) . min (-1) in controls and 19.6 +/- 8.0 degrees vs. 24.1 +/- 5.0 degrees , respectively). Children's self report of satisfaction (with self and health) (p < 0.05), comfort (concerning emotional and physical symptoms and limitations) (p < 0.01) and resilience (positive activities that promote health) (p < 0.01) were significantly decreased in patients with ALL. In summary, children receiving treatment against ALL have overall lower functional capacity and QOL than healthy children. However, their physical condition and health status are sufficiently high to allow them to participate in physical activities and supervised exercise programs.

Can patients with McArdle's disease run?

Patients with McArdle's disease commonly adopt a sedentary lifestyle. This sedentary behaviour, however, usually worsens the limited exercise capacity of these patients. Although eccentric muscle work can be associated with rhabdomyolysis, supervised eccentric training with gradually increasing loads has important advantages compared with conventional concentric work, particularly for patients with a poor cardiorespiratory system. We report the beneficial effects (particularly, increased VO(2peak) (from 14.6 to 30.8 ml/kg/min) and increased gross muscle efficiency (from 13.8% to 17.2%)) induced by a supervised aerobic training programme of 7 months duration including 3-4 running sessions (< or =60 min/session) per week in a 38-year-old patient. These preliminary data suggest the potential therapeutic value of this type of exercise in these patients.

Exercise capacity in a 78 year old patient with McArdle's disease: it is never too late to start exercising.

The case is reported of a 78 year old man with McArdle's disease and a history of treated coronary heart disease. Despite the pre-exercise administration of sucrose allowing the patient to exercise with normal physiological responses, and without typical McArdle's symptoms or biochemical evidence of muscle damage, his exercise capacity was very low (V(O2)peak = 10.7 ml/min/kg), probably attributable to his lifetime of sedentary living. The data suggest that, with pre-exercise sucrose administration, such patients may be candidates for systematic reconditioning, which may improve functional capacity and quality of life.