The Anaerobic Power Assessment in CrossFit ® Athletes: An Agreement Study

capacity are considered determinants of performance and are usually assessed in athletes as a part of their physical capacities' evaluation along the season. For that purpose, many eld tests have been created. The main objective of this study was to analyze the agreement between four eld tests and a laboratory test. Nineteen CrossFit ® (CF) athletes were recruited for this study (28.63 6.62 years) who had been practicing CF for at least one year. Tests performed were: (1) Anaerobic Squat Test at 60% of bodyweight (AST60); (2) Anaerobic Squat Test at 70% of bodyweight (AST70); (3) Repeated Jump Test (RJT); (4) Assault Bike Test (ABT); and (5) Wingate Anaerobic Test on a cycle ergometer (WG). All tests consisted of 30 s of max effort. The differences among methods were tested using a repeated-measures analysis of variance (ANOVA) and effect size. Agreement between methods was performed using Bland–Altman analysis. Analysis of agreement showed systematic bias in all eld test PP values, which varied between 110.05 (AST60 PP—WG PP) and 463.58 (ABT

on a cycle ergometer (WG). All tests consisted of 30 s of max effort. The differences among methods were tested using a repeated-measures analysis of variance (ANOVA) and effect size. Agreement between methods was performed using Bland–Altman analysis. Analysis of agreement showed systematic bias in all eld test PP values, which varied between 110.05 (AST60 PP—WG PP) and 463.58 (ABT PP—WG PP), and a signi cant proportional error in ABT PPby rank correlation (p< 0.001). Repeated-measures ANOVA showed signi cant differences among PP values (F(1.76,31.59) = 130.61,p=< 0.001). In conclusion, since to our knowledge, this is the rst study to analyze the agreement between various methods to estimate anaerobic power in CF athletes. Apart from ABT, all tests showed good agreement and can be used interchangeably in CF athletes. Our results suggest that AST and RJT are good alternatives for measuring the anaerobic power in CF athletes when access to a laboratory is not possible. Keywords: anaerobic power; peak power; HIFT, high-intensity functional training; cross t; athletes; eld test 1. Introduction Anaerobic capacity has been de ned as the total amount of ATP re-synthesized, by the whole body, during a maximal intensity and short duration effort by means of the anaerobic metabolic pathways [1]. The time interval to best measure the anaerobic capacity is 30 s [2] since up to 80% of the energy consumed in 30 s of maximal effort comes from anaerobic sources [3,4]. In addition, in a longer test, individuals tend not to apply the maximum intensity [5]. There are several laboratory tests to assess the anaerobic performance [6]. However, most are expensive and dif cult to perform due to the speci c equipment they require. For that reason, one of the most widely used laboratory tests to assess this ability is the Wingate test, which consists of pedaling with arms or legs at maximum effort for 30 s against a resistance determined by the participant's body weight. WG has shown to be a reliable test, having a test-retest correlation in many populations ranging from 0.89 to 0.98 [7]. Two main variables are determined from this test,

to assess this ability is the Wingate test, which consists of pedaling with arms or legs at maximum effort for 30 s against a resistance determined by the participant's body weight. WG has shown to be a reliable test, having a test-retest correlation in many populations ranging from 0.89 to 0.98 [7]. Two main variables are determined from this test, peak power (PP) and mean power (XP). PP is also known as “anaerobic power” and is determined by the peak mechanical power recorded during the test, normally occurring in the rst 5 to 10 s. In addition, XP is considered by many authors as the “anaerobic capacity” and represents Int. J. Environ. Res. Public Health2021,18, 8878.

Int. J. Environ. Res. Public Health2021,18, 8878 2 of 11 the average mechanical power maintained during the 30 s, taken at 1, 3 or 5 s periods [7]. Some authors have shown PP and XP to be associate with performance in some team and individual sports, especially those performed at high intensity or a combination of low-moderate intensities with higher intensity peaks such as CF [8], sur ng [9], alpine ski [10], soccer [11], track and eld athletes [12] and many others. In order to assess this ability out of the laboratory, numerous eld tests, consisting of different exercises or tasks, have been created. Some of them based on different modalities of jumps [5,12–16]; running [14,17,18]; squat exercise [14,19,20]; and other exercises such as skipping [21]. All those tests have been studied in active individuals [17,18,21,22] as well as athletes of different sports such as soccer [14], volleyball [5,15], track and eld [7,12,20,23], and cyclists [24,25]. They have shown to be valid tools to assess these parameters in athletes [5,12,18,19]. In the last decade, Functional Fitness Training has become one of the top tness trends around the world [26,27]. One of these functional tness programs, which has developed into a competitive sport, was branded as CrossFit ® . CF is a multimodal high- intensity functional training program that combines weightlifting, gymnastics and athletics, among other movements in just one training or competition bout and develops all physical domains such as endurance, strength, stamina, etc. [28]. The multimodality characteristic of this sport, combined with the fact that the tests carried out in competition are not previously announced or standardized, means that CF athletes must be prepared for the unknown and therefore have an optimal development of all physical capacities such as maximum strength, stamina, power, speed, cardiorespiratory tness, etc. [8,29–35]. Additionally, its intensity component indicates that CF competitors must exhibit a great deal of anaerobic performance to excel in this sport [29]. When a eld test is developed to assess any ability of the athletes throughout the season, experts attempt to simulate the speci c sporting gestures of the discipline for

maximum strength, stamina, power, speed, cardiorespiratory tness, etc. [8,29–35]. Additionally, its intensity component indicates that CF competitors must exhibit a great deal of anaerobic performance to excel in this sport [29]. When a eld test is developed to assess any ability of the athletes throughout the season, experts attempt to simulate the speci c sporting gestures of the discipline for which it is created (running in soccer, for example). In the case of CF, as a multimodal sport made up of many elements of different kinds (squatting, jumping, running, lifting, etc.), it might seem challenging to succeed in choosing a speci c exercise that encompasses all the skills and abilities necessary for this activity and evaluate any capacity accurately. Nevertheless, taking into account the speci c characteristics of these athletes, it may be assumed that any eld test might be a valid and interchangeable tool to assess any of the physical capacities. Hence, they might show a good performance in any test with jumping, running, cycling, squatting, etc. In the current work, to assess the anaerobic performance by different exercises and determine their validity and level of agreement, four tests were chosen: a continuous jump test used in previous work by Dal Pupo et al. [5] (RJT), as well as three other tests that, to our knowledge, have not been used previously: two weighted deep squat tests (AST60 and AST70) at different percentages of the athlete's bodyweight (60% and 70%) and a test performed with a particular machine used in CF where upper and lower limbs are used simultaneously called Assault Bike ® (ABT). In CF athletes, some authors have evaluated the physiological determinants of per- formance in [8,30–35]. Most of them using laboratory tests to assess both the aerobic or anaerobic capacities and comparing the results with those obtained in standardized CF workouts. However, no study of agreement between eld methods has been found. There- fore, the main purpose of this study is to analyze the agreement between four different modalities of eld test measuring anaerobic performance (AST60, AST70, RJT and ABT) against the gold standard, Wingate test, in

or anaerobic capacities and comparing the results with those obtained in standardized CF workouts. However, no study of agreement between eld methods has been found. There- fore, the main purpose of this study is to analyze the agreement between four different modalities of eld test measuring anaerobic performance (AST60, AST70, RJT and ABT) against the gold standard, Wingate test, in CF athletes. 2. Materials and Methods 2.1. Participants Nineteen CF participants volunteered to participate in this study, approved by M¡laga University Ethics Committee (CEUMA: 43-2018-H). They were experienced athletes who followed the same competitors' training program and had competed in some national or in-

Int. J. Environ. Res. Public Health2021,18, 8878 3 of 11 ternational competition. Data collection was carried out over four weeks off-season. Except for the rest periods established before each test, the athletes followed their regular training regimen throughout those weeks. They were asked to stop taking any supplementation or performance-enhancing products one week prior to data collection. The participants were recruited and tested in a local CF center. All participants provided written informed consent. As inclusion criteria, a minimum of one year of CF practice was established. Any participants with the presence or suspicion of any cardiac pathology, suffering or having suffered recently any musculoskeletal injury or any other condition that prevented exercising properly were excluded. Descriptive data are shown in Table. Table 1.Descriptive data of the sample (n= 19). Mean SD Age (years) 28.63 6.62 Height (cm) 176.18 5.34 Body Mass (kg) 81.67 6.43 Body Mass Index (kg/m 2 ) 26.29 1.34 Fat Mass (kg) 24.71 6.35 Fat Mass (%) 20.10 5.18 Muscle Mass (kg) 35.03 3.74 Muscle Mass (%) 42.87 2.69 Lean Body Mass (kg) 56.95 10.02 Lean Body Mass (%) 79.90 5.18 2.2. Study Design A cross-sectional study was conducted over four weeks. Despite the fact that all participants were familiar with the exercises in all tests, a familiarization session was also scheduled during the rst two weeks. All trials were separated by at least 48 h and performed at the same daytime to avoid the effects of circadian rhythms [36]. Participants were also advised to refrain from any strenuous physical activity in the previous 24 h of each trial. Tests performed were: (1) Anaerobic Squat Test at 60% of bodyweight (AST60); (2) Anaerobic Squat Test at 70% of bodyweight (AST70); (3) Repeated Jump Test (RJT); (4) Assault Bike Test (ABT); and (5) Wingate Anaerobic Test on a cycle ergometer (WG). Tests order execution was randomly assigned. The chronology of the tests is shown in Figure.Int. J. Environ. Res. Public Health 2021, 18, x FOR PEER REVIEW 4 of 12 SL, Madrid, Spain). Participants were asked to go fasting or without consuming any drink or food for

Assault Bike Test (ABT); and (5) Wingate Anaerobic Test on a cycle ergometer (WG). Tests order execution was randomly assigned. The chronology of the tests is shown in Figure.Int. J. Environ. Res. Public Health 2021, 18, x FOR PEER REVIEW 4 of 12 SL, Madrid, Spain). Participants were asked to go fasting or without consuming any drink or food for at least 4 h, not having consumed alcohol in the last 48 h nor diuretics in the last 7 days or having performed strenuous physical activity in the previous 12 h [37]. Before the measure, they remained supine for 5 min with the upper limbs positioned about 30 degrees apart from the trunk and the lower limbs about 45 degrees apart [38]. Fat mass in kg was estimated according to Segal’s formula [39], Lean body mass in kg was calculated by subtracting fat mass from total body mass and muscle mass in kg according to Janssen’s formula [40]. Body composition variables were also calculated as a percentage (Table 1). Figure 1. The chronology of the tests. 2.3.2. All-Out Anaerobic Tests Anaerobic Squat Test (AST60 and AST70) The AST consisted of 30 s at the maximum effort of deep squats with a percentage of the participant bodyweight. The maximum number of squats had to be performed within that interval. Deep squat was established as a squat in which the iliac crest is below the highest part of the knee in its lowest position, and the leg, thigh and trunk segments are fully aligned at the highest position (Figure 2). The equipment used was a standard olympic lifting set composed of a 20 kg barbell, plates between 5 and 15 kg, with increases of 5 kg, and fractional discs from 0.5 and 2.5 kg, with 0.5 kg increments, from Xenios Usa ® (Xenios Usa LLC, New York, NY, USA). The power of each repetition was registered by Beast ® accelerometry sensor (Beast tech- nologies) attached to the participant’s wrist through a bracelet “ad hoc” (see Figure 3) and data processed by its smartphone application. Beast ® sensor has shown to be a

2.5 kg, with 0.5 kg increments, from Xenios Usa ® (Xenios Usa LLC, New York, NY, USA). The power of each repetition was registered by Beast ® accelerometry sensor (Beast tech- nologies) attached to the participant’s wrist through a bracelet “ad hoc” (see Figure 3) and data processed by its smartphone application. Beast ® sensor has shown to be a valid and reliable tool to measure full-squat values [41]. Two trials with different loads were executed, 60% (AST60) and 70% (AST70) of participant bodyweight. Participants were weighed before each trial to determine the barbell load, rounded to the closest 0.5 kg. As a warm-up, they started with five minutes easy run, followed by one set of ten repetitions with an empty barbell, two more sets of ten repetitions with the assigned percentage and finished with 5 min easy run. Afterwards, a 5 min interval for recovery was established and used to set the accelerometry sensor. At the count of 3, 2, 1... “Go!” the participant began to work at maximum effort, trying to execute as many squats as possible, being verbally motivated by the examiner throughout the test. To cool down, they were asked to easy walk for 5 min. Peak power (PP), mean power (XP) and minimal power (MP) were determined. Fa- tigue index (FI), understood as the loss of power during the 30 s interval, was calculated by the following formula FI (%) = (PP-PM/PP) * 100 [7]. Figure 1.The chronology of the tests.

Int. J. Environ. Res. Public Health2021,18, 8878 4 of 11 2.3. Procedures 2.3.1. Anthropometry, Body Composition and Other Physiological Variables On the rst day, to detect any possible cardiac pathology, all participants underwent an electrocardiogram assessed by a quali ed physician. Furthermore, some anthropometric data were taken; height, by a wall-mounted stadiometer (SECA ® 206; SECA, Hamburg, Germany) with a precision of 1 mm and body mass, by a scale with a precision of 100 gr (SECA ® 803; SECA, Hamburg, Germany). Additionally, body composition was measured by a Medisystem Multifrequency Impedanciometer (Sanocare Human System SL, Madrid, Spain). Participants were asked to go fasting or without consuming any drink or food for at least 4 h, not having consumed alcohol in the last 48 h nor diuretics in the last 7 days or having performed strenuous physical activity in the previous 12 h [37]. Before the measure, they remained supine for 5 min with the upper limbs positioned about 30 degrees apart from the trunk and the lower limbs about 45 degrees apart [38]. Fat mass in kg was estimated according to Segal's formula [39], Lean body mass in kg was calculated by subtracting fat mass from total body mass and muscle mass in kg according to Janssen's formula [40]. Body composition variables were also calculated as a percentage (Table). 2.3.2. All-Out Anaerobic Tests Anaerobic Squat Test (AST60 and AST70) The AST consisted of 30 s at the maximum effort of deep squats with a percentage of the participant bodyweight. The maximum number of squats had to be performed within that interval. Deep squat was established as a squat in which the iliac crest is below the highest part of the knee in its lowest position, and the leg, thigh and trunk segments are fully aligned at the highest position (Figure).Int. J. Environ. Res. Public Health 2021, 18, x FOR PEER REVIEW 5 of 12 Figure 2. Full squat movement requirements. A: start position; B: lowest position; C: final position. Repeated Jump Test (RJT) As previously described by Dal Pupo et al. [5], this test consisted of the maximum number

and trunk segments are fully aligned at the highest position (Figure).Int. J. Environ. Res. Public Health 2021, 18, x FOR PEER REVIEW 5 of 12 Figure 2. Full squat movement requirements. A: start position; B: lowest position; C: final position. Repeated Jump Test (RJT) As previously described by Dal Pupo et al. [5], this test consisted of the maximum number of countermovement jumps in 30 s at the maximum height. Before the trial, par- ticipants warmed up with 5 min easy run, 3 sets of 10 forward jumps, 3 sets of 5 vertical jumps and 5 additional minutes easy run. Afterwards, a 5 min interval was established to rest and set the sensors. At the count of 3, 2, 1… “Go!” the participant started to jump as high and fast as possible. In order to keep the maximum intensity, the participant was encouraged by the researchers during the whole interval. Right after the test, they were asked to easy walk for 5 min to calm down. Jumping variables were registered by a Po- lar ® V800 with Running Bluetooth ® Smart. This sensor has been shown to be valid and reliable to determine jumping variables [42]. PP, XP, MP and FI were determined. Figure 3. Beast sensor placement on the athlete’s at right wrist. Assault Bike Test (ABT) This test was performed with an Assault Bike ® Classic model (Assault Fitness Products; California, USA). The Assault Bike ® is an air-resisted bike with the peculiarity of using both upper and lower extremities simultaneously (Figure 4). This machine has gained its popularity by being used by most CF centers and official competitions worldwide. The test consisted of 30 s at maximal effort. It began with a 15 min warm-up of cycling at 50 rpm (approximately 176 watts). Next, a 5 min recovery interval was es- tablished. The test was carried out from a static position without any inertia. To facilitate the initial start, the crank of the dominant leg was previously set to 45 degrees. Figure 2. Full squat movement requirements. (A): start position; (B): lowest position; (C): final position. The

at 50 rpm (approximately 176 watts). Next, a 5 min recovery interval was es- tablished. The test was carried out from a static position without any inertia. To facilitate the initial start, the crank of the dominant leg was previously set to 45 degrees. Figure 2. Full squat movement requirements. (A): start position; (B): lowest position; (C): final position. The equipment used was a standard olympic lifting set composed of a 20 kg barbell, plates between 5 and 15 kg, with increases of 5 kg, and fractional discs from 0.5 and 2.5 kg, with 0.5 kg increments, from Xenios Usa ® (Xenios Usa LLC, New York, NY, USA). The power of each repetition was registered by Beast ® accelerometry sensor (Beast technologies) attached to the participant's wrist through a bracelet “ad hoc” (see Figure) and data processed by its smartphone application. Beast ® sensor has shown to be a valid and reliable tool to measure full-squat values [41]. Two trials with different loads were executed, 60%

This study analyzes the agreement between four field tests and a laboratory test in CrossFit athletes.