José Luis Maté-Muñoz

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

We assessed the possible association existing between alpha-actinin-3 (ACTN3) R577X genotypes and the capacity for performing aerobic exercise in McArdles patients. Forty adult McArdles disease patients and forty healthy, age and gender-matched sedentary controls (21 men, 19 women in both groups) performed a graded test until exhaustion and a constant-load test on a cycle-ergometer to determine clinically relevant indices of exercise capacity as peak oxygen uptake (VO(2peak)) and the ventilatory threshold (VT). In the group of diseased women, carriers of the X allele had a higher (P<0.01) VO(2peak) (15.0+/-1.2 ml/kg/min) and a higher (P<0.05) oxygen uptake (VO(2)) at the VT (11.2+/-1 ml/kg/min) than R/R homozygotes (VO(2peak): 9.6+/-0.5 ml/kg/min; VO(2) at the VT: 8.2+/-0.7 ml/kg/min). No differences were found in male patients. In women with McArdles disease, ACTN3 genotypes might partly explain the large individual variability that exists in the phenotypic manifestation of this disorder.

Differences in gut microbiota profile between women with active lifestyle and sedentary women

Physical exercise is a tool to prevent and treat some of the chronic diseases affecting the world’s population. A mechanism through which exercise could exert beneficial effects in the body is by provoking alterations to the gut microbiota, an environmental factor that in recent years has been associated with numerous chronic diseases. Here we show that physical exercise performed by women to at least the degree recommended by the World Health Organization can modify the composition of gut microbiota. Using high-throughput sequencing of the 16s rRNA gene, eleven genera were found to be significantly different between active and sedentary women. Quantitative PCR analysis revealed higher abundance of health-promoting bacterial species in active women, including Faecalibacterium prausnitzii, Roseburia hominis and Akkermansia muciniphila. Moreover, body fat percentage, muscular mass and physical activity significantly correlated with several bacterial populations. In summary, we provide the first demonstration of interdependence between some bacterial genera and sedentary behavior parameters, and show that not only does the dose and type of exercise influence the composition of gut microbiota, but also the breaking of sedentary behavior.

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 VO2peak (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 (⩽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.

Double trouble (McArdle's disease and myasthenia gravis): How can exercise help?

We report a 29‐year‐old patient with McArdles disease and myasthenia gravis. She had been debilitated with McArdles disease since childhood (with marked rhabdomyolysis) and was obese. Myasthenia gravis was diagnosed at 24 years of age. After 3 months of aerobic exercise training, her exercise capacity increased significantly and she regained the ability to live independently. We conclude that even patients with profound neuromuscular diseases may benefit from carefully prescribed exercise training. Muscle Nerve, 2006

Can McArdle patients run? A case report

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 VO2peak (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 (⩽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.

Acute Physiological and Mechanical Responses During Resistance Exercise at the Lactate Threshold Intensity.

Abstract Garnacho-Castaño, MV, Domínguez, R, Ruiz-Solano, P, and Maté-Muñoz, JL. Acute physiological and mechanical responses during resistance exercise at the lactate threshold intensity. J Strength Cond Res 29(10): 2867–2873, 2015—The purpose of this study was to examine acute metabolic, mechanical, and cardiac responses to half-squat (HS) resistance exercise performed at a workload corresponding to the lactate threshold (LT). Thirteen healthy subjects completed 3 HS exercise tests separated by 48-hour rest periods: a maximal strength or 1 repetition maximum (1RM) test, an incremental load test to establish the % 1RM at which the LT was reached, and a constant load test at the LT intensity. During the last test, metabolic, mechanical, and cardiac responses were monitored respectively through blood lactate concentrations, height (H), average power (AP) and peak power (PP) recorded in a countermovement jump test, and heart rate (HR). During the constant load test, lactate concentrations and HR remained stable whereas significant reductions were detected in H, AP, and PP (p ⩽ 0.05). Only low correlation was observed between lactate concentrations and the H (r = 0.028), AP (r = 0.072), and PP (r = 0.359) losses produced. Half-squat exercise at the LT elicits stable HR and blood lactate responses within a predominantly aerobic metabolism, although this exercise modality induces significant mechanical fatigue.

Exercise Capacity in a Child With McArdle Disease

We report the exercise capacity of an 8-year-old boy with clinical, histological, biochemical, and genetic evidence of McArdle disease. The patient presented with severe myalgia, proteinuria, hematuria, pyrexia, and elevated creatine kinase after swimming. After pre-exercise ingestion of sucrose, he performed treadmill exercise to symptom limitation. His peak oxygen uptake (18.8 mL/kg/min) and ventilatory threshold (16.0 mL/kg/min) were reduced by 40% and 20% compared with healthy age-matched and gender-matched controls. The results suggest that exercise capacity is reduced early in life in patients with McArdle disease and suggest the need for prophylactic exercise training (following pre-exercise feeding to prevent rhabdomyolysis) to minimize deconditioning.

Muscular fatigue in response to different modalities of CrossFit sessions

Background CrossFit is a new strength and conditioning regimen involving short intense daily workouts called workouts of the day (WOD). This study assesses muscular fatigue levels induced by the three modalities of CrossFit WOD; gymnastics (G), metabolic conditioning (M) and weightlifting (W). Material and methods 34 healthy subjects undertook three WOD (one per week): a G WOD consisting of completing the highest number of sets of 5 pull-ups, 10 push-ups and 15 air squats in 20 min; an M WOD, in which the maximum number of double skipping rope jumps was executed in 8 sets (20 s), resting (10 s) between sets; and finally, a W WOD in which the maximum number of power cleans was executed in 5 min, lifting a load equivalent to 40% of the individuals 1RM. Before and after each WOD, blood lactate concentrations were measured. Also, before, during, and after each WOD, muscular fatigue was assessed in a countermovement jump test (CMJ). Results Significant reductions were produced in the mechanical variables jump height, average power and maximum velocity in response to G; and in jump height, mean and peak power, maximum velocity and maximum force in response to W (P<0.01). However, in M, significant reductions in mechanical variables were observed between pre- and mid session (after sets 2, 4, 6 and 8), but not between pre- and post session. Conclusions Muscular fatigue, reflected by reduced CMJ variables, was produced following the G and W sessions, while recovery of this fatigue was observed at the end of M, likely attributable to rest intervals allowing for the recovery of phosphocreatine stores. Our findings also suggest that the high intensity and volume of exercise in G and W WODs could lead to reduced muscular-tendon stiffness causing a loss of jump ability, related here to a longer isometric phase during the CMJ.

Gait-cycle characteristics and running economy in elite Eritrean and European runners.

PURPOSE This study aimed to determine whether biomechanical characteristics such as ground-contact time, swing time, and stride length and frequency contribute to the exceptional running economy of East African runners. METHODS Seventeen elite long-distance runners (9 Eritrean, 8 European) performed an incremental maximal running test and 3 submaximal running bouts at 17, 19, and 21 km/h. During the tests, gas-exchange parameters were measured to determine maximal oxygen uptake (VO2max) and running economy (RE). In addition, ground-contact time, swing time, stride length, and stride frequency were measured. RESULTS The European runners had higher VO2max values than the Eritrean runners (77.2 ± 5.2 vs 73.5 ± 6.0 mL · kg-1 · min-1, P = .011, effect sizes [ES] = 0.65), although Eritrean runners were more economical at 19 km/h (191.4 ± 10.4 vs 205.9 ± 13.3 mL · kg-1 · min-1, P = .026, ES = 1.21). There were no differences between groups for ground-contact time, swing time, stride length, or stride frequency at any speed. Swing time was associated with running economy at 21 km/h in the Eritrean runners (r = .71, P = .033), but no other significant association was found between RE and biomechanical variables. Finally, best 10-km performance was significantly correlated with RE (r = -.57; P = .013). CONCLUSIONS Eritrean runners have superior RE compared with elite European runners. This appears to offset their inferior VO2max. However, the current data suggest that their better RE does not have a biomechanical basis. Other factors, not measured in the current study, may contribute to this RE advantage.

Circadian rhythm effect on physical tennis performance in trained male players

ABSTRACT To determine the effect of circadian rhythm on neuromuscular responses and kinematics related to physical tennis performance, after a standardised warm-up, 13 highly competitive male tennis players were tested twice for serve velocity/accuracy (SVA), countermovement vertical jump (CMJ), isometric handgrip strength (IS), agility T-test (AGIL) and a 10-m sprint (10-m RUN). In a randomised, counter-balance order, tennis players underwent the test battery twice, either in the morning (i.e., AM; 9:00 h) and in the afternoon (i.e., PM; 16:30 h). Paired t-tests were used to analyse differences due to time-of-day in performance variables. Comparison of morning versus afternoon testing revealed that SVA (168.5 ± 6.5 vs. 175.2 ± 6.1 km · h−1; P = 0.003; effect size [ES] = 1.07), CMJ (32.2 ± 0.9 vs. 33.7 ± 1.1 cm; P = 0.018; ES = 1.46), AGIL (10.14 ± 0.1 vs. 9.91 ± 0.2 s; P = 0.007; ES = 1.23) and 10-m RUN time (1.74 ± 0.1 vs. 1.69 ± 0.1 s; P = 0.021; ES = 0.67) were significantly blunted during the morning testing. However, IS was not affected by time-of-day (P = 0.891). Thus, tennis performance may be reduced when competing in the morning in comparison to early evening. Therefore, coaches and tennis players should focus on schedule the SVA, power, speed and agility training sessions in the afternoon.