Abstract
aimed to compare the acute effect of four back squat velocity-based training (VBT) protocols in terms of intensity (60% vs. 80% of the one repetition maximum [1RM]) and volume (10% vs. 30% threshold for velocity loss in the set) on the maximal aerobic speed (MAS) estimated from a running track test (RTT) in recreationally trained young adult men and women. Twenty par- ticipants (eleven men and nine women) undertook five randomized protocols in separate occasions: (i) RTT alone (control condition); (ii) VBT with 60% 1RM and a 10% velocity loss followed by RTT (VBT 60–10+ RTT ); (iii) VBT with 60% 1RM and a 30% velocity loss followed by RTT (VBT 60–30+ RTT ); (iv) VBT with 80% 1RM and 10% velocity loss followed
men and nine women) undertook five randomized protocols in separate occasions: (i) RTT alone (control condition); (ii) VBT with 60% 1RM and a 10% velocity loss followed by RTT (VBT 60–10+ RTT ); (iii) VBT with 60% 1RM and a 30% velocity loss followed by RTT (VBT 60–30+ RTT ); (iv) VBT with 80% 1RM and 10% velocity loss followed by RTT (VBT 80–10+ RTT); (v) VBT with 80% 1RM and 30% velocity loss followed by RTT (VBT 80–30+ RTT). All VBT protocols involved three sets with three minutes of rest. The MAS was higher for RTT (control) than VBT 60–30+ RTT (p< 0.001;∆= 3.8%), VBT 60–10+ RTT (p= 0.006;∆= 2.8%), VBT 80–10+ RTT (p= 0.008;∆= 2.7%), and VBT 80–30+ RTT (p= 0.019;∆= 1.9%). No protocol×sex interaction was noted (p= 0.422). Therefore, regardless of sex, MAS is acutely impaired after VBT, especially if the training sets are performed with a low relative load and a high velocity loss threshold. Keywords:endurance training; human physical conditioning; musculoskeletal and neural physiological phenomena; resistance training 1. Introduction Running performance depends on the complex interaction of several factors, particu- larly physiological, as well as biomechanical and psychological [1,2]. From a physiological point of view, it is well documented that the ventilatory/lactate threshold, maximal oxygen uptake (VO2max), and running economy are strong performance indicators, especially when the latter are combined, and these indicators determine the maximal aerobic speed (MAS) [2–4]. Therefore, running performance could be improved through central adapta- tions, but also through the ability of athletes to produce more mechanical work for a given energy cost [2,5]. It is therefore not surprising that increased running performance has been reported when resistance and endurance training are incorporated simultaneously within the same program (e.g., “concurrent training”) [1,3,6,7]. However, if exercise variables such as intensity and volume are not adequately prescribed in a concurrent training session, Appl. Sci.2024,14, 2736.
Appl. Sci.2024,14, 2736 2 of 11 resistance training-induced fatigue may acutely impair the quality of subsequent endurance training sessions and induce an interference effect on long-term cardiorespiratory adapta- tions in a phenomenon referred to as “resistance training-induced suboptimization on endurance performance” (RT-SEP) [8,9]. For example, Doma et al. [10] reported impaired running time-to-exhaustion at 110% of the second ventilatory threshold six hours after a resistance training session with heavy loads (six repetitions at ~80% of the one-repetition maximum [1RM]) compared to light loads (total work equated with 20 repetitions) in trained male runners. Relatedly, it has been suggested that heavy loads (≥80% 1RM) may increase susceptibility to RT-SEP [9]. Velocity-based training (VBT) may help to assess optimization (e.g., auto-regulation) and individualization of resistance training intensity and volume according to the training readiness of athletes [11,12], thus reducing chances of RT-SEP [9]. For example, using VBT, Nájera-Ferrer et al. [13] found that compared to a moderate (20%) magnitude of velocity loss during resistance training (three full-squat sets at 60% 1RM), a high (40%) velocity loss resulted in higher metabolic (e.g., greater blood lactate, higher ventilatory equivalents) and mechanical stress (e.g., impaired vertical jump and squat velocity), as well as impaired running performance (e.g., unable to run 10 min at 90% MAS). Sánchez-Moreno et al. [14] observed higher running performance (i.e., MAS) following an eight-week concurrent training program with a moderate rather than high velocity loss (15% > 30%) in the resistance training bouts. Further, 2000 m rowing ergometer time-trial performance was compromised by greater velocity loss in the set (30% vs. 10%), but not by the loading magnitude (60% = 80% of 1RM) [15]. However, further research is needed to gain a deeper understanding of the acute effects of different concurrent VBT protocols, in terms of loading magnitude (60% vs. 80% of 1RM) and velocity loss in the set (10% vs. 30%), on running performance. It has been shown that men reported higher velocities than women for the same %1RM during a variety of resistance training exercises and, consequently, the load-velocity relationship should be sex-specific for a better adjustment of the
VBT protocols, in terms of loading magnitude (60% vs. 80% of 1RM) and velocity loss in the set (10% vs. 30%), on running performance. It has been shown that men reported higher velocities than women for the same %1RM during a variety of resistance training exercises and, consequently, the load-velocity relationship should be sex-specific for a better adjustment of the training intensity [16]. Similarly, it has been reported that recreationally trained men and women can achieve similar increases in strength and power performance following an eight-week VBT program with either 20% or 40% velocity loss, although some results (1RM strength and velocity attained to low/moderate loads) have indicated that strength and power gains favor using 40% rather than 20% velocity loss in women [17]. Therefore, it seems that women require a greater within-set fatigue than men to maximize strength and power development. These authors also observed that men were more susceptible to acute neuromuscular fatigue than women, but these differences in fatigability were reduced after the VBT program [18]. Likewise, Taipale et al. [19] generally observed greater fatigue in terms of decreased maximal and explosive strength in men than in women after a concurrent training session composed of multiple sets of different maximal and explosive strength exercises focused primarily on the leg extensors muscles, along with 10 min of running at ~80% of VO2max. However, although these results are encouraging in addressing the sex gap observed in the scientific literature, there is scarce evidence on how sex could mediate the RT-SEP phenomenon, particularly for the VBT prescription variables (loading magnitude and velocity loss in the set), and its effect on MAS while running. Therefore, this study aimed to examine the acute effect of four different VBT protocols, in terms of loading magnitude (60% vs. 80% 1RM) and velocity loss in the set (10% vs. 30%), on MAS performance estimated from a running track test (RTT) in recreationally trained men and women. We hypothesized that MAS performance would be compromised when the RTT is preceded by the different VBT protocols [9]. Specifically, greater impairment in MAS performance would be expected with
loading magnitude (60% vs. 80% 1RM) and velocity loss in the set (10% vs. 30%), on MAS performance estimated from a running track test (RTT) in recreationally trained men and women. We hypothesized that MAS performance would be compromised when the RTT is preceded by the different VBT protocols [9]. Specifically, greater impairment in MAS performance would be expected with (i) a high relative load along with a high velocity loss threshold in the set [10,15] and (ii) men [18,19].
Appl. Sci.2024,14, 2736 3 of 11 2. Materials and Methods 2.1. Subjects Twenty recreationally trained young adults, 11 men (age = 28.4±6.4 years [range: 19– 38]; body mass = 78.9±11.2 kg; body height = 176.4±6.0 cm; back squat 1RM relative to body mass = 1.8±0.4 kg·kg −1 ; VO2max = 46.0±7.8 mL·kg −1 · min −1 ) and nine women (age = 23.6±2.2 years [range: 21–28]; body mass = 56.1±6.6 kg;body height = 161.7±8.1 cm ; back squat 1RM relative to body mass = 1.6±0.3 kg·kg −1 ; VO2max = 37.2±5.1 mL·kg −1 · min −1 ), volunteered to participate in this study. All subjects had at least one year of resistance and endurance training experience (7.3±5.9 and 10.3±5.9 years for men, and 2.2±1.2 and 9.3±3.4 years for women, respectively) and were familiar with the back-squat and running exercises. No physical limitations, health problems, or musculoskeletal injuries that could compromise testing were reported. In addition, none of the subjects were taking drugs, medications, or dietary supplements to influence physical performance. All subjects were informed about the research purpose and procedures of the study before signing a written informed consent form. The study protocol adhered to the tenets of the Declaration of Helsinki and was approved by the Institutional Review Board. 2.2. Design A randomized-controlled crossover design was used to compare the acute effect between control condition (i.e., RTT) and four different VBT protocols followed by the RTT (VBT60–10+ RTT, VBT60–30+ RTT, VBT80–10+ RTT, and VBT80–30+ RTT) on MAS performance between recreationally trained men and women. Subjects completed the five randomized protocols in sessions separated by 48–72 h (Figure). The Test VAM-HPSS application (version 3.3, University of Murcia, Murcia, Spain) was installed on a Samsung Galaxy A71 smartphone (Samsung, Suwon, South Korean) to estimate VO2max and MAS during each RTT (see below for further details). Both VO2max and MAS estimated from the RTT protocol were very similar to those observed during the laboratory test and gas exchange methods (bias = 0.2 mL·kg −1 · min −1 and <0.1 km·h −1, respectively [20]. Subjects were required to avoid any strenuous exercise throughout
Korean) to estimate VO2max and MAS during each RTT (see below for further details). Both VO2max and MAS estimated from the RTT protocol were very similar to those observed during the laboratory test and gas exchange methods (bias = 0.2 mL·kg −1 · min −1 and <0.1 km·h −1, respectively [20]. Subjects were required to avoid any strenuous exercise throughout the study. All sessions were conducted at the university’s running track, at the same time of the day for each subject (±3 h), and under similar environmental conditions (temperature: 6–15 ◦ C; wind: <8 km·h −1 ). 2.3. Procedures Body mass and body height were measured at the beginning of the first session using a contact electrode foot-to-foot body fat analyzer system (TBF-300A; Tanita Corp of America Inc., Arlington Heights, IL, USA) and a wall-mounted stadiometer (Seca 202; Seca Ltd., Hamburg, Germany), respectively. Each protocol began with the same general warm-up, which consisted of five minutes of running at a self-selected pace, dynamic stretching, and joint mobility exercises. The specific warm-up consisted of two sets of ten air squats and five sub-maximal countermovement jumps, followed by one set of six, four, and two repetitions at 40%, 60%, and 80% of the subjects’ self-perceived back squat 1RM with 3 min of inter-set rest, respectively. After warming up, subjects rested passively for three minutes before beginning each protocol (see Figure). 2.3.1. VBT Protocols Two different relative loads (60% vs. 80% 1RM) and two different magnitudes of velocity loss during the set (10% vs. 30%) were used. Specifically, the configuration of the four VBT protocols was as follows: (i) 60% 1RM with a velocity loss in the set of 10% (VBT60–10), (ii) 60% 1RM with a velocity loss in the set of 30% (VBT60–30), (iii) 80% 1RM with a velocity loss in the set of 10% (VBT80–10), and (iv) 80% 1RM with a velocity loss in the set of 30% (VBT80–30). The relative load of each testing session was determined from the individualized load-velocity relationship using the specific warm-up sets and a minimal velocity threshold of 0.33 m·s −1 [21]. Sets were terminated
(VBT60–30), (iii) 80% 1RM with a velocity loss in the set of 10% (VBT80–10), and (iv) 80% 1RM with a velocity loss in the set of 30% (VBT80–30). The relative load of each testing session was determined from the individualized load-velocity relationship using the specific warm-up sets and a minimal velocity threshold of 0.33 m·s −1 [21]. Sets were terminated when the subjects
Appl. Sci.2024,14, 2736 4 of 11 were unable to complete two consecutive repetitions above the velocity loss limit or with the full range of motion. The fastest repetition from the first set was used to define the target velocity loss limit (e.g., if the fastest velocity is 0.75 m·s −1 , the target velocity used to finish a set would be 0.68 m·s −1 for the 10% velocity loss). The same exercise (back squat), number of sets (three), and inter-set rest (three minutes) were used in all VBT protocols. A validated linear velocity transducer (T-Force system; Ergotech, Murcia, Spain) was used to automatically calculate the mean velocity and provide auditory mean velocity feedback after each repetition [22]. The VBT performance indicators were: (i) the number of repetitions completed in the set, (ii) the fastest velocity of the set, and (iii) the average velocity of the set.Appl. Sci. 2024, 14, x FOR PEER REVIEW 4 of 12 Figure 1. Overview of the experimental design. MAS, maximal aerobic speed; CMJ, countermove- ment jump; 1RM, one-repetition maximum; RTT, running track test; V peak, peak velocity; VBT60–10, velocity-based training (VBT) with 60% of 1RM and a velocity loss (VL) in the set of 10%; VBT 60–30, VBT with 60% of 1RM and a VL in the set of 30%; VBT 80–10, VBT with 80% of 1RM and a VL in the set of 10%; VBT 80–30, VBT with 80% of 1RM and a VL in the set of 30%. 2.3. Procedures Body mass and body height were measured at the beginning of the first session using a contact electrode foot-to-foot body fat analyzer system (TBF-300A; Tanita Corp of Amer- ica Inc., Arlington Heights, IL, USA) and a wall-mounted stadiometer (Seca 202; Seca Ltd., Hamburg, Germany), respectively. Each protocol began with the same general warm-up, which consisted of five minutes of running at a self-selected pace, dynamic stretching, and joint mobility exercises. The specific warm-up consisted of two sets of ten air squats and five sub-maximal countermovement jumps, followed by one set of six, four, and two rep- etitions at 40%, 60%, and 80% of
Germany), respectively. Each protocol began with the same general warm-up, which consisted of five minutes of running at a self-selected pace, dynamic stretching, and joint mobility exercises. The specific warm-up consisted of two sets of ten air squats and five sub-maximal countermovement jumps, followed by one set of six, four, and two rep- etitions at 40%, 60%, and 80% of the subjects’ self-perceived back squat 1RM with 3 min of inter-set rest, respectively. After warming up, subjects rested passively for three minutes before beginning each protocol (see Figure 1). Figure 1.Overview of the experimental design. MAS, maximal aerobic speed; CMJ, countermovement jump; 1RM, one-repetition maximum; RTT, running track test; V peak, peak velocity; VBT 60–10, velocity- based training (VBT) with 60% of 1RM and a velocity loss (VL) in the set of 10%; VBT 60–30, VBT with 60% of 1RM and a VL in the set of 30%; VBT 80–10, VBT with 80% of 1RM and a VL in the set of 10%; VBT 80–30, VBT with 80% of 1RM and a VL in the set of 30%. The back-squat technique involved subjects standing with the knees and hips fully extended, feet approximately shoulder-width apart, and the barbell held across the top
Appl. Sci.2024,14, 2736 5 of 11 of the shoulders and upper back. From this position, they were required to descend in a continuous motion until their buttocks made contact with a wooden box and, immediately after, return to the initial position as fast as possible. The height of the wooden box was individually set at 90 ◦ of knee flexion with a manual goniometer (Goniómetro Rulong, Fisaude, Spain). 2.3.2. RTT Protocol TheTest VAM-HPSSapplication was used to determine running performance (MAS and VO2max) following the manufacturer’s instructions. First, the RTT protocol was selected based on the subjects’ self-reported peak velocity: (i) <17.0 km·h −1 (>41.0 min in a 10-km race), 17.0–19.0 km·h −1 (36.5–41.0 min in a 10-km race), and >19.0 km·h −1 (<36.0 min in a 10-km race). Second, subjects completed five minutes of running at low intensity, two ten- second progressive runs, and three minutes of walking as part of the specific warm-up. Third, subjects received an auditory “ready, set” cue before beginning the RTT protocol with a beep signal. After pressing the start button, the stopwatch, distance, and velocity fields were launched in theTest VAM-HPSSapplication. Subjects were previously instructed to reach each cone located every 25 m around a running track while they regulated their running pace according to the beep signals. The frequency of the beep signal was automatically set according to the peak velocity selected for each RTT protocol. All auditory cues and beep signals were provided by theTest VAM-HPSSapplication connected to a loudspeaker. The RTT protocol ended when the subjects were unable to reach the cone at the time of the beep signal on two consecutive occasions, or they voluntarily decided to stop running after perceiving maximal exertion. The peak heart rate (HR) was recorded with a Polar H10 chest strap (Polar Electro Oy, Kempele, Finland) during the RTT, and the Borg’s category-ratio 10 scale (CR-10) was reported after the test. The HR and CR-10 were used as maximal effort criteria [23]. The Test VAM-HPSSapplication automatically estimated the MAS and VO2max from the peak velocity achieved in each RTT [ 2.4. Statistical Analyses Descriptive data
with a Polar H10 chest strap (Polar Electro Oy, Kempele, Finland) during the RTT, and the Borg’s category-ratio 10 scale (CR-10) was reported after the test. The HR and CR-10 were used as maximal effort criteria [23]. The Test VAM-HPSSapplication automatically estimated the MAS and VO2max from the peak velocity achieved in each RTT [ 2.4. Statistical Analyses Descriptive data are presented as mean±SDs. The Shapiro-Wilk test confirmed the normal distribution of all variables (p> 0.05), except for CR-10. A one-way repeated-measures analysis of variance (ANOVA) and Friedman test were used to compare peak HR and CR- 10 between protocols, respectively. A mixed model ANOVA was conducted on each VBT performance indicator (numbers of repetitions, fastest velocity, and average velocity) with the protocol and set as within-subject factor and sex as between-subject factor. A mixed model ANOVA was applied to the MAS, with the protocol as a within-subject factor and sex as a between-subject factor. The Greenhouse-Geisser correction was used when Mauchly’s sphericity test was violated and pairwise comparisons were identified using Bonferroni post hoc corrections. The magnitude of the differences was quantified through the standardized mean differences (Cohen’sdeffect size [ES]). The following scale was used to interpret the magnitude of the ES:trivial(<0.20),small(0.20–0.59),moderate(0.60–1.19),large(1.20–2.00), and extremely large(>2.00) [24]. All statistical analyses were performed using the software package SPSS (IBM SPSS version 25.0, Chicago, IL, USA) and statistical significance was set at an alpha level of 0.05.Post hocstatistical power was conducted using G*Power (Version 3.1) with an ES of 0.30 andαof 0.05, and this revealed a 0.93 statistic power. 3. Results 3.1. Descriptive Characteristics of the VBT Protocols The main effect of protocol was significant for the number of repetitions, fastest velocity, and average velocity (F (3,54)≥ 46.9;p< 0.001). A significant main effect of set was only reported for the fastest velocity (F (2,36)= 4.3;p= 0.021). Finally, the protocol×sex interaction for the fastest and average velocity (F (3,54)= 5.8 and 4.9;p= 0.002 and 0.005, respectively) and protocol×set interaction for the average velocity (F (6,108)= 3.9;p= 0.002) also reached statistical significance (Table).
Description
The study compares the effects of different VBT protocols on running performance.