Delayed Effect of Dry-Land Strength Training Sessions on Swimming Performance

he purpose of the study was to examine the effects of dry-land strength endurance (SE) and maximum strength (MS) sessions on next-day swimming performance. Eight swim- mers (age:18.6 2.9 years) performed evening training sessions (19:00–19:40), including: (i) SE (2 15 20 repetitions, 50% of 1-RM), (ii) MS (2 5 repetitions, 90% of 1-RM), (iii) control (CON: no dry-land training). All sessions were followed by a 90-min swimming training (20:00–21:30). Medicine ball throw and countermovement jump, free countermovement jump and squat jump were evaluated before and after the dry-land training session and 12 h later, before a 100-m front crawl sprint (next day at 8:30 a.m.). Performance time, RPE, blood lactate and biomechanical variables in 100-m sprint were no different between conditions (time, MS: 64.70 7.35, SE: 63.81 7.29, CON: 64.52 7.71 s ,p> 0.05). Jump height was not changed before and after dry-land and before the 100-m sprint

training session and 12 h later, before a 100-m front crawl sprint (next day at 8:30 a.m.). Performance time, RPE, blood lactate and biomechanical variables in 100-m sprint were no different between conditions (time, MS: 64.70 7.35, SE: 63.81 7.29, CON: 64.52 7.71 s ,p> 0.05). Jump height was not changed before and after dry-land and before the 100-m sprint in all conditions (p> 0.05). Medicine ball throw was lower in MS compared to CON before the 100-m sprint (MS: 4.44 1.11, vs. CON: 4.66 1.21 m,p< 0.05). Upper-body but not lower- body muscle function may be affected by MS training. However, performance in a 100-m test is not affected by dry-land training performed 12 h earlier. Keywords:strength training; swimming; performance evaluation; biomechanical variables 1. Introduction Dry-land strength endurance (SE) or maximum strength sessions (MS) may be per- formed a few minutes prior to swimming training [1]. These priming dry-land sessions may deteriorate swimmers' performance or technique during the following swimming training session [2,3]. However, in a pre-competition setting, especially during the general preparation phase of training, the swimmers participate in a session involving concurrent resistance training and swimming some hours before a competition. Evidence indicates that a morning concurrent dry-land and swimming session may enhance an afternoon swimmer's 100-m performance time [4]. Moreover, 50-m front crawl performance was improved 24 h after a priming dry-land strength endurance and power training [5]. As such, priming dry-land strength training, even with heavy loads ( 85% of 1-repetition maximum), seems to be bene cial for athletic performance up to 48 h as a delayed potentia- tion effect [6]. Similar ndings have been reported following strength training with heavy loads contributing to power athletes' performance improvements and increments in their lower-body power output the following day [7]. The abovementioned ndings indicate that when 6 to 24 h of recovery has been completed following a speci c resistance training session, this may be bene cial to performance [4–7]. The recovery period after a strength J. Funct. Morphol. Kinesiol.2023,8, 87.

the following day [7]. The abovementioned ndings indicate that when 6 to 24 h of recovery has been completed following a speci c resistance training session, this may be bene cial to performance [4–7]. The recovery period after a strength J. Funct. Morphol. Kinesiol.2023,8, 87.

J. Funct. Morphol. Kinesiol.2023,8, 87 2 of 10 training session with heavy loads may present a biphasic recovery of performance (i.e., 11 h and 11 to 22 h) that may be attributed to structural muscle changes (excitation–contraction coupling) [8]. Previous research indicated a higher energy cost during a running economy test following resistance training session and decreased performance the following day [9]. A 12-h period of recovery may be practically applicable to swimmers following an afternoon and a morning session or competition. This information about the effect of dry-land strength training on the following day, however, remains unknown in swimming and needs further research. The aim of the current study is to examine the acute effect of priming dry-land strength endurance and maximum strength training sessions on swimming performance the following day. We hypothesized that dry-land strength training performed 12 h before a 100-m sprint test would negatively affect performance compared with control condition (no dry-land training). 2. Materials and Methods 2.1. Experimental Approach to the Problem A one-group repeated-measures design was applied in the study, including three experimental conditions. Swimmers with a counterbalanced order performed a control session and two equal total load dry-land strength training sessions; strength endurance (SE) and maximum strength (MS) in an afternoon training and performance in a 100-m sprint test was evaluated 12 h later (the following morning). Countermovement jump (CMJ), free countermovement jump with arm swing (FCMJ), squat jump (SJ) and medicine ball throw (MBT) were used to evaluate muscle function in the experimental sessions. All the experimental procedures were completed in three weeks, during the swimmers' general preparation period. 2.2. Participants Eight competitive swimmers (5 males and 3 females) from the same swimming club volunteered to participate in the study. Swimmers' anthropometric and performance characteristics are shown in Table. Swimmers did not take any dietary supplements of any kind or medication, and they were free from injury. All the participants were familiar and had at least two years of experience with dry-land strength training protocols. The local institutional review board approved the experimental procedures (approval number: 1111), which were in accordance with

and performance characteristics are shown in Table. Swimmers did not take any dietary supplements of any kind or medication, and they were free from injury. All the participants were familiar and had at least two years of experience with dry-land strength training protocols. The local institutional review board approved the experimental procedures (approval number: 1111), which were in accordance with the Declaration of Helsinki. All the participants and their legal guardians signed an informed consent following a detailed explanation of the experimental procedures. Table 1. Anthropometric, performance and training characteristics of swimmers who participated in the study. Variables Overall swimmers (n = 8) Male Swimmers (n = 5) Female Swimmers (n = 3) Age (years) 18.6 2.9 19.6 3.1 17.7 2.2 Body mass (kg) 65.6 10.2 67.9 5.6 64.6 3.4 Body height (cm) 172.4 6.4 174.6 3.3 168.6 2.8 Arm-span (cm) 176.2 8.2 177.4 4.5 171.6 3.2 Seated height (cm) 90.4 4.3 91.8 3.6 90.5 4.5 Body fat (%) 16.9 4.0 15.5 2.2 19.4 2.1 Body mass index (kg/m 2 ) 21.4 2.3 22.0 2.1 21.7 1.9 100-m sprint time (s) 60.5 7.7 56.3 2.4 65.3 3.2 FINA points (100-m front crawl) 555.6 12.1 590.4 14.5 497.6 12.3 Competitive experience (years) 9.8 1.6 10.2 2.3 9.3 1.5 Dry-land training experience (years) 2.0 2.2 2.3 1.6 2.0 1.0 FINA: F²d²ration Internationale de Natation Amateur.

J. Funct. Morphol. Kinesiol.2023,8, 87 3 of 10 2.3. Testing Procedures 2.3.1. Preliminary Testing and Familiarization Session During the rst session, swimmers' anthropometric characteristics were evaluated. Body mass, body height and arm-span were measured. Body mass index and body fat per- centage were calculated using the Jackson and Pollock equations [10]. In the second session, swimmers' one-repetition maximum (1RM) in bench press, seated pull rowing, (swimmers were permitted to move their torso during the pull), and half squat (knee angle at 90 ), were measured using standard procedures (ICC = 0.96, 0.98 and 0.98, respectively) [11]. In the third and fourth sessions, the swimmers were familiarized with the dry-land strength exercises that were performed in the experimental conditions. Familiarization included the three main exercises—bench press, seated pull rowing, and half squat—performing 2 to 3 sets of 15 to 20 repetitions, with a preferred external load in each exercise and 2 sets of 15 to 20 repetitions of sit ups and back extensions as secondary exercises. The aim of the familiarization session was to standardize swimmers' technique in dry-land strength training sessions. 2.3.2. Experimental Conditions Each swimmer completed in a random order: (i) SE (2 15 20 repetitions, 50% of 1-repetition maximum); (ii) MS (2 5 repetitions, 85% of 1-repetition maximum); (iii) no dry-land (control: CON) in a 40-min afternoon session (18:00–18:40 p.m.). SE, MS and CON sessions were followed by the same content 90-min in-water swimming training (19:00–20:30 p.m.). Upper-body muscle performance was evaluated using a 3-kg medicine ball throw. Lower-body performance was evaluated by a CMJ, a FCMJ and a SJ, before and after each dry-land training session and the respective time moments in the CON condition. All upper- and lower-body performance tests were repeated 12 h later, in the next morning session and before a 100-m front crawl sprint test at 8:30 a.m. Heart rate (HR), rating of perceived exertion (RPE) and blood lactate concentration (BL) were measured before the start and after the 100-m front crawl sprint test. During 100-m sprint test, split time measurement (50-m), arm-stoke rate (SR), and arm-stroke length (SL) were calculated. The experimental

the next morning session and before a 100-m front crawl sprint test at 8:30 a.m. Heart rate (HR), rating of perceived exertion (RPE) and blood lactate concentration (BL) were measured before the start and after the 100-m front crawl sprint test. During 100-m sprint test, split time measurement (50-m), arm-stoke rate (SR), and arm-stroke length (SL) were calculated. The experimental procedures of the study were conducted in an outdoor 50-m swimming pool with a constant water temperature of 27 C. The experimental protocol is illustrated in Figure. 2.3.3. Dry Land Strength Training Both dry-land strength training sessions, SE and MS, consisted of the same ve exercises that have been previously included in dry-land sessions for competitive swim- mers [2,12]. The SE and MS training sessions' characteristics are shown in Table. The training volume of SE and MS sessions was equalized by manipulating the number of sets, number of repetitions, load/intensity and movement tempo during repetition, as shown in Equation (1). Training volume=Sets Repetitions %1 RM MT (1) where %1-RM (repetition maximum) is the training load/intensity and MT is the movement tempo during a repetition in bench press, seated pulley rowing or half squat. The training volume for SE and MS sessions in arbitrary units is shown in Table. 2.3.4. Low Intensity Swimming Interval Training Swimmers performed a low-intensity swimming interval training 20 min after the completion of the SE and MS sessions. Speci cally, swimming training consisted of a 1000-mstandardized warm-up (600-m choice swimming, 4 50-m front crawl drills, 4 50-m front crawl kicks); 6 200-m individual medley with 30 s of rest between repetitions while focusing on technique; a 2000-m main set (5 400-m front crawl) with a low intensity corresponding to a HR of 140 to 150 b min 1 and a 30 s rest between

J. Funct. Morphol. Kinesiol.2023,8, 87 4 of 10 repetitions; and a 300-m recovery/cool down period. The volume of the swimming training session was 4500 m, and the overall duration was about 90 min. Table 2. Detailed description of the dry-land strength endurance and maximum strength training sessions performed by the swimmers twelve hours prior to 100-m sprint test performed during the next day's morning session. 1RM: one-repetition maximum.Dry-Land Strength Endurance Training Session (SE) Exercises Number of Sets Number of Repetitions Intensity (%1-RM) Rest Movement Tempo/Repetition Bench press 2 20 55 20 s 2 s/repetition Seated pulley rowing 2 20 55 20 s 2 s/repetition Sit-ups 3 15 Body weight 30 s Preferred Back extension 3 15 Body weight 30 s Preferred Half squat (knee angle 90 ) 2 20 55 20 s 2 s/repetition Overall duration 20 min Dry-Land Maximum Strength Training Session (MS) Exercises Number of Sets Number of Repetitions Intensity (%1-RM) Rest Movement Tempo/Repetition Bench press 3 4 90 3 min 4 s/repetition Seated pulley rowing 3 4 90 3 min 4 s/repetition Sit-ups 3 15 Body weight 30 s Preferred Back extension 3 15 Body weight 30 s Preferred Half squat (knee angle 90 ) 3 4 90 3 min 4 s/repetition Overall duration 26 min 2 s/repetition: 1 s lifting and 1 s lowering, 4 s/repetition: 2 s lifting and 2 s lowering.J. Funct. Morphol. Kinesiol. 2023, 8, x FOR PEER REVIEW 4 of 11 Figure 1. Experimental design of the study. ↑ indicates the testing evaluations of the lower limbs, such as countermovement jump (CMJ), free countermovement jumps (FCMJ) and squat jump (SJ), ● indicates the testing evaluation of the upper limbs, such as medicine ball throwing (MBT). BL: blood lactate concentration; SR: arm-stroke rate; SL: arm-stroke length; RPE: rate of perceived exer- tion; HR: heart rate. 2.3.3. Dry Land Strength Training Both dry-land strength training sessions, SE and MS, consisted of the same five exer- cises that have been previously included in dry-land sessions for competitive swimmers [2,12]. The SE and MS training sessions’ characteristics are shown in Table 2. The training volume of

SL: arm-stroke length; RPE: rate of perceived exer- tion; HR: heart rate. 2.3.3. Dry Land Strength Training Both dry-land strength training sessions, SE and MS, consisted of the same five exer- cises that have been previously included in dry-land sessions for competitive swimmers [2,12]. The SE and MS training sessions’ characteristics are shown in Table 2. The training volume of SE and MS sessions was equalized by manipulating the num- ber of sets, number of repetitions, load/intensity and movement tempo during repetition, as shown in Equation (1). Training volumeLSets HRepetitions H%1FRM HMT (1) where %1-RM (repetition maximum) is the training load/intensity and MT is the move- ment tempo during a repetition in bench press, seated pulley rowing or half squat. The training volume for SE and MS sessions in arbitrary units is shown in Table 2. Figure 1. Experimental design of the study."indicates the testing evaluations of the lower limbs, such as countermovement jump (CMJ), free countermovement jumps (FCMJ) and squat jump (SJ), indicates the testing evaluation of the upper limbs, such as medicine ball throwing (MBT). BL: blood lactate concentration; SR: arm-stroke rate; SL: arm-stroke length; RPE: rate of perceived exertion; HR: heart rate.

J. Funct. Morphol. Kinesiol.2023,8, 87 5 of 10 2.4. Dry-Land Performance Evaluations 2.4.1. Upper Limb Evaluation Swimmers' upper-limb performance was evaluated through medicine ball seated push throw distance (MBT) in a seated position, as described by Dorie et al. [13]. Initially, the swimmers were familiarized with the MBT procedure of performing two MBT trials. Then, swimmers performed a two-minute warm-up using the medicine ball with different weights (2 to 5 kg). Two minutes after the warm-up, the swimmers performed three exercises from a seated position with 60 s of rest between each trial using a 3-kg medicine ball (Amila, Greece). Two experienced researchers measured the horizontal distance of displacement in ball throwing. The average MBT distance was included in the statistical analysis. 2.4.2. Lower Limb Evaluation CMJ [14], FCMJ with arm swing and SJ [15] were measured on a portable device (Optojump Next, Bolzano, Italy). The Optojump photoelectric system consists of two parallel bars positioned approximately one meter apart at the floor level. The bars were connected to a computer with the appropriate software that measures the flight time of vertical jumps with an accuracy of 1/1000 (1 kHz). After a standardized warm-up consisting of five minutes of low-intensity running, one warm-up trial in each jump technique and dynamic stretching, the swimmers performed three exercises in CMJ, FCMJ, and SJ. A 30-s and 120-s rest was allowed between each exercise and each jump technique, respectively. The average height displacement from each jump technique was used in the statistical analysis. 2.4.3. Swimming 100-m Sprint on the following Day At 8:30 a.m. of the morning following each SE, MS and CON session a 100-m front crawl sprint test was conducted after a 1000-m warm-up. Immediately after the completion of the 100-m test, HR was recorded (Polar Electro, Kempele, Finland) and RPE was indicated (0–10 points Borg scale) [16]. A ngertip blood sample was collected before the start and three minutes after 100-m sprint test to measure blood lactate concentration (Lactate scout, Germany) [17]. During the 100-m test, SR was calculated as the time to complete three stroke cycles, and SL was calculated

HR was recorded (Polar Electro, Kempele, Finland) and RPE was indicated (0–10 points Borg scale) [16]. A ngertip blood sample was collected before the start and three minutes after 100-m sprint test to measure blood lactate concentration (Lactate scout, Germany) [17]. During the 100-m test, SR was calculated as the time to complete three stroke cycles, and SL was calculated by the ratio of swimming speed to SR in each 50-m split. In addition, an experienced timekeeper recorded swimmers' performance times (Casio HS-80, Hubei, China). 2.5. Statistical Analyses The normal distribution of the data was tested using the Kolmogorov Smirnov test. The sphericity was verified using the Mauchly test. When the assumption of Sphericity was not met, the significance ofFratios was adjusted according to the Greenhouse- Geiser procedure. Analysis of variance on repeated measures was used to compare BL, SR, SL, CMJ, FCMJ, SJ and MBT (three conditions time points). A Tukey honest significant difference as a post-hoc test was used to compare the means when significant F-ratios were found. In addition, a one-way analysis of variance was used to compare the performance times in the 100-m front crawl test, HR and RPE. To estimate the size of the main effects and interaction, the partial eta squared (h 2) values from the analysis of variance were used. Considering the sample size (N = 8), an effect sizedof 0.80 was required to obtain a statistical power greater than 0.85 [18]. ICC using 1-way random effects was used to test reliability. Data are presented as mean and SD. Statistical significance was set atp< 0.05. 3. Results 3.1. Dry-Land Performance Evaluations The MBT distance was no different between conditions (F2,14= 1.22,h 2= 0.15,p= 0.32) and between the time points of measurement (F2,14= 2.67,h 2= 0.27,p= 0.10). However, the

J. Funct. Morphol. Kinesiol.2023,8, 87 6 of 10 MBT distance was decreased by 4.4 8.2% the following day, before the 100-m test, after MS compared to CON condition (F2,14= 4.50,h 2= 0.39,p= 0.01, Figure). CMJ, FCMJ and SJ were higher in SE compared to MS, while no difference was found compared to CON (p< 0.05, see Figure). In addition, CMJ, FCMJ and SJ were similar at all time points of measurement (p> 0.05, Figure).J. Funct. Morphol. Kinesiol. 2023, 8, x FOR PEER REVIEW 7 of 11 found. In addition, a one-way analysis of variance was used to compare the performance times in the 100-m front crawl test, HR and RPE. To estimate the size of the main effects and interaction, the partial eta squared (η 2 ) values from the analysis of variance were used. Considering the sample size (N = 8), an effect size d of 0.80 was required to obtain a statis- tical power greater than 0.85 [18]. ICC using 1-way random effects was used to test relia- bility. Data are presented as mean and SD. Statistical significance was set at p < 0.05. 3. Results 3.1. Dry‐Land Performance Evaluations The MBT distance was no different between conditions (F 2,14 = 1.22, η 2 = 0.15, p = 0.32) and between the time points of measurement (F 2,14 = 2.67, η 2 = 0.27, p = 0.10). However, the MBT distance was decreased by 4.4 ± 8.2% the following day, before the 100-m test, after MS compared to CON condition (F 2,14 = 4.50, η 2 = 0.39, p = 0.01, Figure 2). CMJ, FCMJ and SJ were higher in SE compared to MS, while no difference was found compared to CON (p < 0.05, see Figure 2). In addition, CMJ, FCMJ and SJ were similar at all time points of measurement (p > 0.05, Figure 2). Figure 2. Acute effect of three experimental conditions, dry-land strength endurance (SE), dry-land maximum strength (MS) and control (CON) in dry-land performance evaluation of lower limbs in three different techniques: countermovement jump (CMJ; panel a); free countermovement jump (FCMJ; panel b);

This study investigates the impact of dry-land strength training on swimming performance the following day.