Local Muscle Endurance and Strength Had Strong Relationship with CrossFit ® Open 2020 in Amateur Athletes

dy analyzed the relationship between anthropometric measures, cardiorespiratory capacity, strength, power, and local muscle endurance with performance in the CrossFit ® Open 2020. For this, 17 volunteers (6 women) (29.0 7.2 years) completed, on separate weeks, tests for body composition (dual-energy X-ray absorptiometry), maximal oxygen consumption (2 km row test), muscle strength (one repetition maximum (1 RM) back and front squat, isometric peak torque), muscle power (1 RM snatch and clean and jerk) and muscle endurance (Tibana test), which were compared with performance

For this, 17 volunteers (6 women) (29.0 7.2 years) completed, on separate weeks, tests for body composition (dual-energy X-ray absorptiometry), maximal oxygen consumption (2 km row test), muscle strength (one repetition maximum (1 RM) back and front squat, isometric peak torque), muscle power (1 RM snatch and clean and jerk) and muscle endurance (Tibana test), which were compared with performance during the CrossFit ® Open 2020. Speci c tests of localized muscular endurance and muscle strength had the strongest relationship with performance in the CrossFit ® Open 2020. On the other hand, the percentage of fat and cardiorespiratory capacity were not signi cantly correlated with CrossFit ® Open 2020 workout performance. Coaches and practitioners should therefore utilize these ndings to assess physical tness and organize the distribution of the training session based on less developed physical needs, in order to ensure an appropriate physiological adaptation for a given competition. Keywords:functional tness training; athletic performance; exercise testing 1. Introduction CrossFit ® is considered as a constantly varied, high-intensity, functional movement training aiming at increasing work capacity across multiple physical domains (endurance, strength, exibility) using several functional movements [1]. Therefore, different types of workout sessions, which are known as Workout of the Day (WOD), combine differ- ent exercises and tasks, such as cycling, running, rowing, Olympic weightlifting, power weightlifting and gymnastic-type exercises [1]. Competitive CrossFit ® often consists of two stages, the online quali er (multiple unfamiliar workout challenges that are completed over the course of some weeks) from which the competitors with the best online results qualify for regional events (South America, North America, Africa, Asia etc.). The CrossFit ® Open is an online competition of cially managed by CrossFit Inc, and is one of the largest sports events in the world, with more than 239,106 participants in the 2020 event. The speci c training for the CrossFit ® Open tends to be different for regional events (South America, North America, Africa, Asia etc.), due to the characteristics of that compe- Sports2021,9, 98.

world, with more than 239,106 participants in the 2020 event. The speci c training for the CrossFit ® Open tends to be different for regional events (South America, North America, Africa, Asia etc.), due to the characteristics of that compe- Sports2021,9, 98.

Sports2021,9, 98 2 of 10 tition (low overload is usually used in resistance exercises and tasks with longer duration). In addition, only rowing ergometer is traditionally prescribed as a cyclic exercise (usually with low volume). Despite the increase in popularity, there is a paucity of literature on the topic of CrossFit performance. Previous research has investigated the relationship between non-speci c tests such as anthropometric pro le [2], cardiorespiratory capacity [3], muscle strength [3], and muscle power [3], with performance in practitioners and athletes of CrossFit. For example, Mart½nez-Gâmez et al. [3] evaluated the relationship between muscle strength (full squat) and performance at the CrossFit ® Open 2017. The authors showed that strength and power indices measured in a squat test were positively associated with CrossFit ® performance. However, according to Butcher et al. [4], performance in CrossFit is different from most sports where it is possible to predict and evaluate the performance of an athlete with tests of muscular strength, physiological variables, and aerobic and anaerobic powers (test on treadmill and Wingate, respectively). In CrossFit, although the tests are partially associated with performance in some tests (CrossFit open and benchmarks), these tests have no speci city with the variety of movements and repetitions during the workouts (calisthenics, strength, and endurance). The workouts in the previous year (2019) had no characteristics of muscle strength or cardiovascular capacity. On the other hand, the athletes performed several repetitions of speci c exercises, such as a gymnastic component (e.g., burpees, strict handstand push-ups or walks, chest to bar pull-ups, toes-to-bar, and bar muscle-ups) with relatively light resis- tance exercises (e.g., wall ball, thruster, clean, snatch, dumbbell overhead lunge, dumbbell box step-ups). However, it is unknown whether a speci c test of local muscle endurance is associated with performance in the CrossFit ® Open. Prior physical performance screening might provide ef cient data for analysis and important feedback to athletes and coaches to determine key performance predictors in a particular competition. This information could be valuable for evidence-based strategies during competitions and to identify possible de cient performance. Therefore, the current study aimed to

endurance is associated with performance in the CrossFit ® Open. Prior physical performance screening might provide ef cient data for analysis and important feedback to athletes and coaches to determine key performance predictors in a particular competition. This information could be valuable for evidence-based strategies during competitions and to identify possible de cient performance. Therefore, the current study aimed to analyze the relationship between anthropo- metric measures, cardiorespiratory capacity, and the variables of strength, power, and a speci c test of muscular endurance with performance in the CrossFit ® Open 2020. We hypothesized that signi cant correlations would be found between the variables analyzed and performance in the CrossFit ® Open 2020. 2. Materials and Methods 2.1. Participants In total, 17 volunteers (6 women) (29.0 7.2 years) were recruited. All subjects were free of injury or known illnesses, were not using performance enhancing drugs, and had a minimum of 6 months of CrossFit experience. Participants were advised to sleep six to eight hours the night before the tests, maintain regular nutritional and hydration habits, avoid intense exercise 48 h prior to the sessions, and avoid smoking, alcohol, and caffeine consumption 24 h before a session. All subjects provided informed consent and the study was approved by the University Research Ethics Committee for Human Use (2.698.225/Universidade Est¡cio de S¡/UNESA/RJ) and conformed to the principles of the Helsinki Declaration on the use of human participants for research. 2.2. Experimental Design The present study followed a cross-sectional design. All participants performed the baseline assessments two weeks prior to the CrossFit ® Open 2020 ( ve workouts for 5 weeks) (October–November 2019). Figure methodological steps in the present study.

Sports2021,9, 98 3 of 10Sports 2021, 9, x FOR PEER REVIEW 3 of 11 Figure 1. Description of study timeline. 2.3. Baseline Assessments The participants performed, on separate weeks, body composition (dual-energy X- ray absorptiometry), maximal oxygen consumption (2 km row test), muscle strength (1 RM back squat, 1 RM front squat and isometric peak torque, Biodex System 3), and muscle power measures (1 RM snatch and 1 RM clean and jerk), as well as a specific test of muscle endurance (Tibana test). Baseline assessments were performed two weeks before the CrossFit ® Open 2020. 2.4. Anthropometric Measurements The anthropometric measurements were made in the morning after an overnight fast, with the subjects wearing light clothing and no shoes. The participants were weighed on a Filizola ® digital scale (Curitiba, PR, Brazil; capacity of 180 kg) to the nearest 0.1 kg. Each subject was measured in accordance with the standard methods proposed by the Interna- tional Society for the Advancement of Kinanthropometry [5]. 2.5. Body Composition The body composition evaluation, including body fat percentage and fat-free mass, was performed through dual energy X-ray absorptiometry (General Electric-GE model 8548 BX1L, year 2005, Lunar DPX type, software Encore 2005; Rommelsdorf, Germany) with a coefficient of variation of 0.9–1.1%. Briefly, the examinations included a complete body scan of the participants in a supine position. The equipment was continuously reg- ulated and operated by a technically trained health professional. Legs were secured by nonelastic straps at the knees and ankles, and the arms were aligned along the trunk with the palms facing the thighs. 2.6. Maximal Oxygen Consumption The 2 km row test was performed as previously described by Jensen et al. [6]. All exercise tests were performed on the same rowing ergometer (model E; Concept 2, Mor- risville, VT, USA). The subjects individually adapted their preferred stroke rate and drag factor in tests and during the warm-up protocol. The standardized warm-up for the 2 km time trail was 4 min of easy rowing; 4 × 1 min with 10, 15, 20, and 10 hard strokes for each minute; and 2 min of easy

E; Concept 2, Mor- risville, VT, USA). The subjects individually adapted their preferred stroke rate and drag factor in tests and during the warm-up protocol. The standardized warm-up for the 2 km time trail was 4 min of easy rowing; 4 × 1 min with 10, 15, 20, and 10 hard strokes for each minute; and 2 min of easy rowing. After a short rest while the oxygen uptake equipment was mounted, the 2 km all-out time trail was performed. Figure 1.Description of study timeline. 2.3. Baseline Assessments The participants performed, on separate weeks, body composition (dual-energy X-ray absorptiometry), maximal oxygen consumption (2 km row test), muscle strength (1 RM back squat, 1 RM front squat and isometric peak torque, Biodex System 3), and muscle power measures (1 RM snatch and 1 RM clean and jerk), as well as a speci c test of muscle endurance (Tibana test). Baseline assessments were performed two weeks before the CrossFit ® Open 2020. 2.4. Anthropometric Measurements The anthropometric measurements were made in the morning after an overnight fast, with the subjects wearing light clothing and no shoes. The participants were weighed on a Filizola ® digital scale (Curitiba, PR, Brazil; capacity of 180 kg) to the nearest 0.1 kg. Each subject was measured in accordance with the standard methods proposed by the International Society for the Advancement of Kinanthropometry [5]. 2.5. Body Composition The body composition evaluation, including body fat percentage and fat-free mass, was performed through dual energy X-ray absorptiometry (General Electric-GE model 8548 BX1L, year 2005, Lunar DPX type, software Encore 2005; Rommelsdorf, Germany) with a coef cient of variation of 0.9–1.1%. Brie y, the examinations included a complete body scan of the participants in a supine position. The equipment was continuously regulated and operated by a technically trained health professional. Legs were secured by nonelastic straps at the knees and ankles, and the arms were aligned along the trunk with the palms facing the thighs. 2.6. Maximal Oxygen Consumption The 2 km row test was performed as previously described by Jensen et al. [6]. All exercise tests were performed on

continuously regulated and operated by a technically trained health professional. Legs were secured by nonelastic straps at the knees and ankles, and the arms were aligned along the trunk with the palms facing the thighs. 2.6. Maximal Oxygen Consumption The 2 km row test was performed as previously described by Jensen et al. [6]. All exercise tests were performed on the same rowing ergometer (model E; Concept 2, Mor- risville, VT, USA). The subjects individually adapted their preferred stroke rate and drag factor in tests and during the warm-up protocol. The standardized warm-up for the 2 km time trail was 4 min of easy rowing; 4 1 min with 10, 15, 20, and 10 hard strokes for each minute; and 2 min of easy rowing. After a short rest while the oxygen uptake equipment was mounted, the 2 km all-out time trail was performed.

Sports2021,9, 98 4 of 10 Before and during the test period, athletes were monitored by ECG (Digital Electrocar- diogram, Micromed Brazil, S¢o Paulo, SP, Brazil) to detect possible anomalies that would make it impossible for the volunteers to continue the test or study. Heart rate (HR) was measured with a Polar H10 (Polar Electro Oy, Kemple, Finland). Gases were analyzed using the ERGOPc ELITE/Metaso t 3 device (Bras½lia, DF, Brazil). The VO 2peakand HR values adopted were the highest achieved during the test. All procedures were followed by a cardiologist. 2.7. Muscle Strength and Power Measures Participants performed one repetition maximum (1 RM) test for back squat, front squat, snatch, and clean and jerk according to procedures recommended by the National Strength and Conditioning Association [7,8] with 48 h rest intervals between sessions to minimize the muscle fatigue effects and pain. All randomized tests were performed with a barbell (20/15 kg) and weights (1–25 kg) (Pood Fitness ® , Bras½lia, DF, Brazil). The test protocol consisted of a brief general warm-up on a bike or indoor rowing ergometer, followed by eight repetitions at 50% of estimated 1 RM (according to the prior loads used by members in their training exercise routines). Following a 1 min rest, they performed three repetitions at 70% of estimated 1 RM. Then, the participants completed three to ve attempts with 3 to 5 min rest intervals between each attempt, with progressively heavier weights until the 1 RM was established. All testing sessions took place between 2 p.m. and 3 p.m. after lunch and under a controlled standardized temperature (25 C). During this exercise period, standard instructions regarding the procedures of the test protocols and the appropriate execution of the exercise technique were supplied by a quali ed and experienced investigator. 2.8. Isometric Strength The subjects were seated in a knee extension chair that allowed for isometric force assessment. Subjects were restrained in the chair with straps secured around their chest, abdomen, and hips. Their arms remained crossed during testing. Three maximal isometric contractions of knee extension were performed on the isokinetic dynamometer (Biodex System 3,

quali ed and experienced investigator. 2.8. Isometric Strength The subjects were seated in a knee extension chair that allowed for isometric force assessment. Subjects were restrained in the chair with straps secured around their chest, abdomen, and hips. Their arms remained crossed during testing. Three maximal isometric contractions of knee extension were performed on the isokinetic dynamometer (Biodex System 3, Biodex Medical Systems, Shirley, NY, USA). The knee joint was xed at 60 for performance of the isometric contraction for a period of 5 s, with the subject seated and hips xed at a 90 angle [9]. A 3 min recovery period was provided between isometric contractions. The highest value was considered as the maximum isometric torque [9]. 2.9. Local Muscle Endurance The local muscle endurance test applied was the Tibana test, which included the conclusion of four distinct rounds of work, each separated by 2 min of rest (Figure). Speci cally, the rounds involved 4 min of as many rounds as possible (AMRAP) of ve thrusters (60 kg for men and 43 kg for women) and 10 box jumps over (round 1); 4 min of AMRAP of 10 power clean (60 kg for men and 43 kg for women) and 20 pull-ups (round 2); 4 min of AMRAP of 15 shoulder to overhead (60 kg for men and 43 kg for women) and 30 toes to bar (round 3); and 4 min of AMRAP of 20 calories of rowing and 40 wall ball (9 kg for men and 6 kg for women) (round 4) [10,11]. 2.10. CrossFit ® Open 2020 The speci c details of the ve workouts of the day (WODs) used in this study, known as 20.1, 20.2, 20.3, 20.4, and 20.5, are brie y explained below: 20.1: Participants had 15 min to complete 10 rounds of the following exercises: 8 ground-to-overheads (43 kg men; 29.5 kg women) and 10 bar-facing burpees. 20.2: Participants had 20 min to complete as many rounds as possible of 4 dumbbell thrusters (22.5 kg for men and 16 kg for women—dumbbells), 6 toes-to-bars, and 24 double-unders.

20.1: Participants had 15 min to complete 10 rounds of the following exercises: 8 ground-to-overheads (43 kg men; 29.5 kg women) and 10 bar-facing burpees. 20.2: Participants had 20 min to complete as many rounds as possible of 4 dumbbell thrusters (22.5 kg for men and 16 kg for women—dumbbells), 6 toes-to-bars, and 24 double-unders.

Sports2021,9, 98 5 of 10 20.3: Participants had 9 min to complete 21 deadlifts, 102/70 kg, 21 handstand push- ups 15 deadlifts, 102/70 kg, 15 handstand push-ups, 9 deadlifts, 102/70 kg, 9 hand- stand push-ups, 21 deadlifts, 143/93 kg, 15 m handstand walk, 15 deadlifts, 143/93 kg, 15 m handstand walk, 9 deadlifts, 143/93 kg and 15 m handstand walk. 20.4: Participants had 20 min to complete 30 box jumps, 60/50 cm, 15 clean and jerks, 43/29.5 kg, 30 box jumps, 60/50 cm, 15 clean and jerks, 61/39 kg, 30 box jumps, 60/50 cm, 10 clean and jerks, 84/52 kg, 30 single-leg squats, 10 clean and jerks, 102/66 kg, 30 single-leg squats, 5 clean and jerks, 125/80 kg, 30 single leg squats, and 5 clean and jerks, 143/93 kg. 20.5: Participants had 20 min to complete 40 muscle-ups, 80-cal row, 120 wall-ball shots, (9 kg ball to 3 m/6 kg ball to 2.75 m).Sports 2021, 9, x FOR PEER REVIEW 5 of 11 Figure 2. Description of the local muscle endurance test (Tibana test): 4 min of as many rounds as possible (AMRAP) of five thrusters, and 10 box jump over (round 1); 2 min of rest; 4 min of AMRAP of 10 power clean, and 20 pull-ups (round 2); 2 min of rest; 4 min of AMRAP of 15 shoulder to overhead, and 30 toes to bar (round 3); 2 min of rest; and 4 min of AMRAP of 20 calories of row, and 40 wall ball (round 4). 2.10. CrossFit ® Open 2020 The specific details of the five workouts of the day (WODs) used in this study, known as 20.1, 20.2, 20.3, 20.4, and 20.5, are briefly explained below: • 20.1: Participants had 15 min to complete 10 rounds of the following exercises: 8 ground-to-overheads (43 kg men; 29.5 kg women) and 10 bar-facing burpees. • 20.2: Participants had 20 min to complete as many rounds as possible of 4 dumbbell thrusters (22.5 kg for men and 16 kg for women—dumbbells), 6 toes-to-bars, and 24 double-unders. • 20.3: Participants had 9 min to complete 21 deadlifts, 102/70

The study explores the correlation between muscle endurance and performance in the CrossFit Open 2020.