Polygenic risk scores associate with blood pressure traits across the lifespan

AIMS

Hypertension is a major modifiable cause of morbidity and mortality that affects over 1 billion people worldwide. Blood pressure (BP) traits have a strong genetic component that can be quantified with polygenic risk scores (PRSs). To date, the performance of BP PRSs has mainly been assessed in adults, and less is known about polygenic hypertension risk in childhood.

METHODS AND RESULTS

Multiple PRSs for systolic BP (SBP), diastolic BP (DBP), and pulse pressure were developed using either genome-wide significant weights, pruning and thresholding, or Bayesian regression. Among 87 total PRSs, the top performer for each trait was applied in independent cohorts of children and adult to assess genotype-phenotype associations and disease risk across the lifespan. Differences between those with low (1st decile), average (2nd-9th decile), and high (10th decile) PRS emerge in the first years of life and are maintained throughout adulthood. These diverging BP trajectories also seem to affect cardiovascular and renal disease risk, with increased risk observed among those in the top decile and reduced risk among those in the bottom decile of the polygenic risk distribution compared with the rest of the population.

CONCLUSION

Genetic risk factors are associated with BP traits across the lifespan, beginning in the first years of life. Given the importance of exposure time in disease pathogenesis and the early rise in BP levels among those genetically susceptible, PRSs may help identify high-risk individuals prior to hypertension onset, facilitate primordial prevention, and reduce the burden of this public health challenge.

Sex-specific and polygenic effects underlying resting heart rate and associated risk of cardiovascular disease

AIMS

Resting heart rate (RHR) is associated with cardiovascular disease (CVD) and mortality. This study aimed to identify genetic loci associated with RHR, develop a genome-wide polygenic risk score (PRS) for RHR, and assess associations between the RHR PRS and CVD outcomes, to better understand the biological mechanisms linking RHR to disease. Sex-specific analyses were conducted to potentially elucidate different pathways between the sexes.

METHODS

We performed a genome-wide meta-analysis of RHR (n=550,467) using two independent study populations, The Trøndelag Health Study (HUNT) and the UK Biobank (UKB), comprising 69,155 and 481,312 participants, respectively. We also developed a genome-wide PRS for RHR using UKB and tested for association between the PRS and 13 disease outcomes in HUNT.

RESULTS

We identified 403, 253, and 167 independent single nucleotide polymorphisms (SNPs) significantly associated with RHR in the total population, women, and men, respectively. The sex-specified analyses indicated differences in the genetic contribution to RHR and revealed loci significantly associated with RHR in only one of the sexes. The SNPs were mapped to genes enriched in heart tissue and cardiac conduction pathways, as well as disease-pathways, including dilated cardiomyopathy. The PRS for RHR was associated with increased risk of hypertension and dilated cardiomyopathy, and decreased risk of atrial fibrillation.

CONCLUSION

Our findings provide insight into the pleiotropic effects of the RHR variants, contributing towards an improved understanding of mechanisms linking RHR and disease. In addition, the sex-specific results might contribute to a more refined understanding of RHR as a risk factor for the different diseases.

Healthcare costs associated with overweight and obesity at an individual versus a population level - a HUNT study

BACKGROUND

The interpretation of research results is affected by how results are presented. We show the importance of presenting the association between body mass index (BMI) and healthcare costs from both the individual perspective and the population perspective.

MATERIAL AND METHOD

Using measurements of height and weight from the Nord-Trøndelag Health Study (HUNT Study) linked to register data on specialist healthcare costs and demographics, we estimated the association between BMI and specialist healthcare costs by means of regression analyses.

RESULTS

From an individual perspective, the association between BMI and specialist healthcare costs was strongest in people in obesity classes 2 and 3 (BMI ≥ 35 kg/m2). In contrast, from a population perspective, the association was strongest in the case of overweight (BMI ≥ 25 kg/m2) or obesity class 1 (BMI ≥ 30 kg/m2), as there are more people in this BMI range.

INTERPRETATION

The study emphasises the importance of including the population perspective in research studies and policy decision-making processes. People with severe obesity have a high individual risk, but their use of health services has less significance for the overall costs of health care since they are fewer people in this group.

Position before submission? Techniques and tactics in competitive no-gi Brazilian jiu-jitsu

Brazilian jiu-jitsu (BJJ) is a grappling-based combat sport performed either with a traditional uniform, the gi, or without, known as no-gi. Differences between the two when it comes to gripping, pace, and ruleset can affect match characteristics, which has implications for how athletes approach competition. The present study investigated time-motion and technical-tactical characteristics in matches from official no-gi submission-only BJJ tournaments. The analysis included 26 regional and 26 international athletes from the light-feather to super-heavy weight class. Match characteristics did not differ between competition levels, style (guard or pass player), or weight (p > 0.05). The duration of positional dominance was similar between competition levels and styles (p > 0.05), but significantly different between winners and losers (p < 0.05; effect size (ES) = 0.39). Positional dominance also correlated with upper-body submissions (r = 0.50; p < 0.05). Interestingly, positional dominance appeared inconsequential in matches determined by lower-body submissions. In fact, athletes winning by lower-body submissions, in most cases a heel hook, exerted no positional control prior to their victory. The high- to low-intensity ratio was 1:2 and 1:1, for regional and international athletes, respectively. The standing to ground time ratio was 1:2 for both groups. In addition to the novel competition characteristics of competitive no-gi BJJ, these findings indicate that there are strategical discrepancies that precede distinctly different submission holds.

The effects of straight and alternating sets on volume load, training efficiency, and metabolic response in grapplers

BACKGROUND

The importance of strength in Brazilian jiu-jitsu (BJJ) has inspired several recommendations of resistance training (RT) in BJJ athletes, yet little is known about their responses to different RT approaches. Thus, we aimed to investigate volume, efficiency, and fatigue responses in two popular RT protocols.

METHODS

In a randomized crossover design, 12 male BJJ athletes (mean age: 24.5±3.1 years; height: 175±5 cm; body mass: 77.1±12.9 kg; body fat: 14.3±5.7%; BMI: 24.8±3.0) completed two separate RT protocols consisting of the same exercises performed either as straight sets (TRAD) or alternating sets (AST) for three sets to failure with a previously established 10-repetition maximum (10RM) load. Maximal number of repetitions (MNR), training duration, volume load (VL), and training efficiency (TE = VL/time), rating of perceived exertion (RPE), and blood lactate concentration (LAC) were assessed in each protocol.

RESULTS

MNR decreased steadily from first to last sets for all exercises, with no difference between protocols (P>0.05), resulting in the same VL. The shorter duration of AST resulted in increased TE (P<0.001), which was accompanied by higher RPE (P<0.001) and LAC (P<0.05), as well as higher session perceived load (P<0.01).

CONCLUSIONS

Given the role of VL as a driver of RT adaptations, both approaches may be suitable for improvements in strength and hypertrophy. The distinct differences in duration and metabolic response should be considered when implementing RT alongside regular sport training.

Aerobic interval training improves maximal oxygen uptake and reduces body fat in grapplers

BACKGROUND

Despite regularly engaging in high-intensity grappling, Brazilian jiu-jitsu (BJJ) athletes have a moderate maximal oxygen uptake (V̇O2max). The aim of this study was to evaluate the efficacy and feasibility of high-intensity aerobic interval training as an accessory to BJJ training for improvements in V̇O2max.

METHODS

Twelve active male BJJ practitioners (age: 30.3±4.0 [SD] years; height: 183.0±5.3 cm; body mass: 82.7±8.3 kg; body fat: 11.9±3.8%) with 5.6±5.8 years of experience and a training volume of 9.9±4.6 hours·week-1 were randomly allocated to either a training group (TG) or control group (CG). The TG incorporated two high-intensity aerobic interval training sessions·week-1 comprising four 4-minute intervals at 85-95% of maximal heart rate (HRmax) separated by 3-minute active breaks at 70% of HRmax.

RESULTS

After six weeks, the TG increased their V̇O2max by 8±3% (95% CI=3.84, 12.73; P=0.04; ES=0.64), from 52.7 to 56.8 mL·kg-1·min-1. This was accompanied by a 1±1% reduction in absolute body fat (95% CI=-0.13, -2.2; P=0.04; ES=0.64). No changes in V̇O2max (P=0.12) or body composition (P=0.34) were detected in the CG.

CONCLUSIONS

These findings reveal compelling short-term effects of low-volume high-intensity aerobic interval training on V̇O2max and body composition in active BJJ athletes. There may be a ceiling effect in terms of developing V̇O2max in supine, intermittent grappling sports, making alternative approaches to aerobic conditioning particularly relevant for this athlete population.

Maximal Strength Training Improves Strength Performance in Grapplers

Øvretveit, K and Tøien, T. Maximal strength training improves strength performance in grapplers. J Strength Cond Res 32(12): 3326-3332, 2018-The aim of this study was to assess the short-term effects of maximal strength training (MST) as an accessory to grappling training on strength performance in competitive Brazilian Jiu-Jitsu (BJJ) athletes. Fourteen male BJJ athletes underwent measurements of 1 repetition maximum (1RM) in the squat and bench press, rate of force development (RFD) and peak force (PF) in the squat jump, countermovement jump (CMJ) height, and muscular endurance in pull-ups, sit-ups, and push-ups. After baseline measurements, subjects were randomly allocated to either an MST group or control group (CON). The MST intervention consisted of 4 × 4 repetitions at ≥ 85% of 1RM in the squat and bench press, and 4 sets of pull-ups to failure, performed 3× per week. Both groups were instructed to maintain their BJJ training and avoid additional strength training. Maximal strength training improved 1RM in the squat and bench press by 15 ± 9% (p = 0.02) and 11 ± 3% (p = 0.03), respectively, and CMJ height by 9 ± 7% (p = 0.04). Muscular endurance performance increased by 33 ± 33% in pull-ups (p = 0.03), 32 ± 12% in push-ups (p = 0.03), and 13 ± 13% in sit-ups (p = 0.03). Increases in RFD (35 ± 55%, p = 0.13) and PF (8 ± 9%, p = 0.09) did not reach significance. No improvements were apparent from BJJ training alone (p > 0.05). These findings suggest that MST is a potent approach to rapid improvements in maximal strength, power, and muscular endurance in active grapplers.

Anthropometric and Physiological Characteristics of Brazilian Jiu-Jitsu Athletes

Øvretveit, K. Anthropometric and physiological characteristics of Brazilian jiu-jitsu athletes. J Strength Cond Res 32(4): 997-1004, 2018-The aim of this study was to describe anthropometric and physiological characteristics of Brazilian jiu-jitsu (BJJ) athletes. For this purpose, 42 male athletes were recruited from one of the largest BJJ academies in central Norway. The subjects were 32 ± 6 (SD) years old, 181.9 ± 7.2 cm tall, had a body mass (mb) of 85.7 ± 10.6 kg, and 5.5 ± 3.7 years of BJJ training experience. The subjects underwent segmental multifrequency bioelectrical impedance analysis of body composition (BIA), direct measurements of pulmonary function and maximal oxygen uptake (V[Combining Dot Above]O2max), assessments of 1-repetition maximum (1RM) in the parallel squat and paused bench press, and one set of pronated-grip pull-ups to muscular failure. The average body fat percentage (BF) was 12.9 ± 5.3%. The subjects achieved a V[Combining Dot Above]O2max of 50.6 ± 4.6 mL·kg·min. Absolute squat 1RM (113.2 ± 20.4 kg) was significantly higher than bench press 1RM (87.6 ± 16.5 kg) (p < 0.001). The mean number of pull-ups achieved was 9 ± 4. These characteristics were generally independent of rank, training experience, weekly training volume, competition volume, and style preference. Additional strength training was associated with improved bench press performance (p < 0.05). Beyond that, additional strength and/or conditioning training had no apparent relationship with any variable (p > 0.05). This study provides novel insight into the fitness levels of BJJ athletes. These findings indicate the degree of exercise response to BJJ training and are applicable in athlete assessment and exercise prescription in this population.