The Development of a Resting Metabolic Rate Prediction Equation for Professional Male Rugby Union Players.

Determining resting metabolic rate (RMR) is an important aspect when calculating energy requirements for professional rugby union players. Prediction equations are often used for convenience to estimate RMR. However, the accuracy of current prediction equations for professional rugby union players remains unclear. The aims of this study were to examine the RMR of professional male rugby union players compared to nine commonly used prediction equations and develop and validate RMR prediction equations specific to professional male rugby union players. One hundred and eight players (body mass (BM) = 102.9 ± 13.3 kg; fat-free mass (FFM) = 84.8 ± 10.2 kg) undertook Dual-energy X-ray Absorptiometry scans to assess body composition and indirect calorimetry to determine RMR. Mean RMR values of 2585 ± 176 kcal∙day-1 were observed among the group with forwards (2706 ± 94 kcal·day-1), demonstrating significantly (p < 0.01; d = 1.93) higher RMR compared to backs (2465 ± 156 kcal·day-1), which appeared to be due to their higher BM and FFM measures. Compared to the measured RMR for the group, seven of the nine commonly used prediction equations significantly (p < 0.05) under-estimated RMR (-104-346 kcal·day-1), and one equation significantly (p < 0.01) over-estimated RMR (192 kcal·day-1). This led to the development of a new prediction equation using stepwise linear regression, which determined that the strongest predictor of RMR for this group was FFM alone (R2 = 0.70; SEE = 96.65), followed by BM alone (R2 = 0.65; SEE = 104.97). Measuring RMR within a group of professional male rugby union players is important, as current prediction equations may under- or over-estimate RMR. If direct measures of RMR cannot be obtained, we propose the newly developed prediction equations be used to estimate RMR within professional male rugby union players. Otherwise, developing team- and/or group-specific prediction equations is encouraged.

Dietary Intakes of Elite Male Professional Rugby Union Players in Catered and Non-Catered Environments.

In professional rugby union, it is common for players to switch between catered and non-catered dietary environments throughout a season. However, little is known about the difference in dietary intake between these two settings. Twelve elite male professional rugby union players (28.3 ± 2.9 y, 188.9 ± 9.5 cm, 104.1 ± 13.3 kg) from the New Zealand Super Rugby Championship completed seven-day photographic food diaries with two-way communication during two seven-day competition weeks in both catered and non-catered environments. While no significant differences were observed in relative carbohydrate intake, mean seven-day absolute energy intakes (5210 ± 674 vs. 4341 ± 654 kcal·day-1), relative protein (2.8 ± 0.3 vs. 2.3 ± 0.3 g·kgBM·day-1) and relative fat (2.1 ± 0.3 vs. 1.5 ± 0.3 g·kgBM·day-1) intakes were significantly higher in the catered compared to the non-catered environment (respectively) among forwards (n = 6). Backs (n = 6) presented non-significantly higher energy and macronutrient intakes within a catered compared to a non-catered environment. More similar dietary intakes were observed among backs regardless of the catering environment. Forwards may require more support and/or attention when transitioning between catered and non-catered environments to ensure that recommended dietary intakes are being achieved.

The Influence of Full-Time Holistic Support Delivered by a Sports Nutritionist on Within-Day Macronutrient Distribution in New Zealand Provincial Academy Rugby Union Players.

Dietary intake is an important consideration for rugby union ('rugby') players to ensure substrate provision for optimal performance and facilitate recovery. Within-day meal distribution is especially important for athletes, particularly those with congested schedules and multiple daily training sessions. In the present study, 10 provincial academy rugby players engaged in a holistic support protocol informed by behaviour-change techniques led by a full-time sports nutritionist. Dietary intake was estimated during a 4-week monitoring and 4-week intervention period using the remote food photography method on one high-volume training day (two training sessions) and two low-volume training days (≤1 training session) per week. Lean body mass did not change significantly in response to the intervention. Significant increases were observed for protein on both low-volume (breakfast, AM snack, evening snack) and high-volume (post-gym, AM snack, evening snack) training days. Carbohydrate intake post-intervention was significantly greater at the pre-gym eating occasion but lower at PM snack and dinner eating occasions on high-volume days. These data suggest that incorporating a holistic support protocol led by a sports nutritionist can influence within-day nutrient intake in rugby players; however, no change to lean body mass was observed, and the influence of these changes in nutrient intake on performance and recovery warrants further investigation.

Competition Nutrition Practices of Elite Male Professional Rugby Union Players.

Thirty-four elite male professional rugby union players from the New Zealand Super Rugby championship completed dietary intakes via the Snap-N-Send method during a seven-day competition week. Mean seven-day absolute energy intake was significantly higher for forwards (4606 ± 719 kcal·day-1) compared to backs (3761 ± 618 kcal·day-1; p < 0.01; d = 1.26). Forwards demonstrated significantly higher mean seven-day absolute macronutrient intakes compared to backs (p < 0.03; d = 0.86-1.58), but no significant differences were observed for mean seven-day relative carbohydrate (3.5 ± 0.8 vs. 3.7 ± 0.7 g·kg·day-1), protein (2.5 ± 0.4 vs. 2.4 ± 0.5 g·kg·day-1), and fat (1.8 ± 0.4 vs. 1.8 ± 0.5 g·kg·day-1) intakes. Both forwards and backs reported their highest energy (5223 ± 864 vs. 4694 ± 784 kcal·day-1) and carbohydrate (4.4 ± 1.2 vs. 5.1 ± 1.0 g·kg·day-1) intakes on game day, with ≈62% of total calories being consumed prior to kick-off. Mean pre-game meal composition for all players was 1.4 ± 0.5 g·kg-1 carbohydrate, 0.8 ± 0.2 g·kg-1 protein, and 0.5 ± 0.2 g·kg-1 fat. Players fell short of daily sports nutrition guidelines for carbohydrate and appeared to "eat to intensity" by increasing or decreasing energy and carbohydrate intake based on the training load. Despite recommendations and continued education, many rugby players select what would be considered a "lower" carbohydrate intake. Although these intakes appear adequate to be a professional RU player, further research is required to determine optimal dietary intakes.

The Physical Characteristics of Elite Female Rugby Union Players.

This study explored the anthropometric and body composition characteristics of elite female rugby union players, comparing between and within different playing positions. Thirty elite female rugby union players (25.6 ± 4.3 y, 171.3 ± 7.7 cm, 83.5 ± 13.9 kg) from New Zealand participated in this study. Physical characteristics were assessed using anthropometric (height, body mass, skinfolds) and body composition (dual-energy X-ray absorptiometry) measures. Forwards were significantly taller (p < 0.01; d = 1.34), heavier (p < 0.01; d = 2.19), and possessed greater skinfolds (p < 0.01; d = 1.02) than backs. Forwards also possessed significantly greater total (p < 0.01; d = 1.83-2.25) and regional (p < 0.01; d = 1.50-2.50) body composition measures compared to backs. Healthy bone mineral density values were observed in both forwards and backs, with significantly greater values observed at the arm (p < 0.01; d = 0.92) and femoral neck (p = 0.04; d = 0.77) sites for forwards. Tight-five players were significantly heavier (p = 0.02; d = 1.41) and possessed significantly greater skinfolds (p < 0.01; d = 0.97) than loose-forwards. Tight-five also possessed significantly greater total body composition measures (p < 0.05; d = 0.97-1.77) and significantly greater trunk lean mass (p = 0.04; d = 1.14), trunk fat mass (p < 0.01; d = 1.84), and arm fat mass (p = 0.02; d = 1.35) compared to loose-forwards. Specific programming and monitoring for forwards and backs, particularly within forward positional groups, appear important due to such physical characteristic differences.

Physical and Fitness Characteristics of Elite Professional Rugby Union Players.

This study explored the physical and fitness characteristics of elite professional rugby union players and examined the relationships between these characteristics within forwards and backs. Thirty-nine elite professional rugby union players from the New Zealand Super Rugby Championship participated in this study. Body composition was measured using dual-energy X-ray absorptiometry alongside anthropometrics. Fitness characteristics included various strength, power, speed, and aerobic fitness measures. Forwards were significantly (p = < 0.01) taller and heavier than backs, and possessed greater lean mass, fat mass, fat percentage, bone mass, and skinfolds. Forwards demonstrated greater strength and absolute power measures than backs (p = 0.02), but were slower and possessed less aerobic fitness (p = < 0.01). Skinfolds demonstrated very large correlations with relative power (r = -0.84) and speed (r = 0.75) measures within forwards, while backs demonstrated large correlations between skinfolds and aerobic fitness (r = -0.54). Fat mass and fat percentage demonstrated very large correlations with speed (r = 0.71) and aerobic fitness (r = -0.70) measures within forwards. Skinfolds, fat mass, and fat percentage relate strongly to key fitness characteristics required for elite professional rugby union performance. Individual and positional monitoring is important due to the clear differences between positions.

The Acute Potentiating Effects of Heavy Sled Pulls on Sprint Performance.

This study examined the acute potentiating effects of heavy sprint-style sled pulls on sprint performance. Twenty-two experienced resistance-trained rugby athletes performed 2 heavy sprint-style sled pull training protocols on separate occasions using a randomized, crossover, and counterbalanced design. The protocols consisted of 2-baseline 15 m sprints followed by 15 m sprints at 4, 8, and 12 minutes after completing 15 and 7.5 m heavy sled pulls with loads of 75 and 150% body mass (respectively). A significantly faster (p ≤ 0.05) 15 m sprint time was observed at 12 minutes for the 75% body mass load. Small nonsignificant improvements (effect size [ES] = 0.22-0.33) in 5, 10, and 15 m sprint times were observed at 8 and 12 minutes after the 75% body mass sled pull. No significant changes were observed for any sprint time after the 150% body mass sled pull. Significant differences in the percentage of change in sprint times between the 2 sled pull conditions were observed at 4 (ES = 0.44-0.52), 8 (ES = 0.59), and 12 minutes (ES = 0.64). It would seem that the 75% body mass sled pull can be an effective preload stimulus for improving subsequent sprint performance provided that adequate recovery (8-12 minutes) is allowed. Practitioners should be advised that prescription of training load based on decrement in sprint velocity may be the best approach to determine loading for athletes.

Strongman vs. traditional resistance training effects on muscular function and performance.

Currently, no evidence exists as to the effectiveness of strongman training programs for performance enhancement. This study compared the effects of 7 weeks of strongman resistance training vs. traditional resistance training on body composition, strength, power, and speed measures. Thirty experienced resistance-trained rugby players were randomly assigned to one of the 2 groups; strongman (n = 15; mean ± SD: age, 23.4 ± 5.6 years; body mass, 91.2 ± 14.8 kg; height, 180.1 ± 6.8 cm) or traditional (n = 15; mean ± SD: age, 22.5 ± 3.4 years; body mass, 93.7 ± 12.3 kg; height, 181.3 ± 5.9 cm). The strongman and traditional training programs required the participants to train twice a week and contained exercises that were matched for biomechanical similarity with equal loading. Participants were assessed for body composition, strength, power, speed, and change of direction (COD) performance. Within-group analyses indicated that all performance measures improved with training (0.2-7%) in both the strongman and traditional training groups. No significant between-group differences were observed in functional performance measures after 7 weeks of resistance training. Between-group differences indicated small positive effects in muscle mass and acceleration performance and large improvements in 1 repetition maximum (1RM) bent over row strength associated with strongman compared with traditional training. Small to moderate positive changes in 1RM squat and deadlift strength, horizontal jump, COD turning ability, and sled push performance were associated with traditional compared with strongman training. Practitioners now have the first evidence on the efficacy of a strongman training program, and it would seem that short-term strongman training programs are as effective as traditional resistance training programs in improving aspects of body composition, muscular function, and performance.