Abstract
is study compared the acute physiological responses and performance changes dur- ing an integrated high-intensity interval aerobic and power protocol. Sixteen moderately trained athletes (age: 20.1±2.2 years, body height: 180.0±6.5 cm, body mass: 75.7±6.4 kg, VO 2max: 55.8±4.3 mL/kg/min) performed a 2×6 min interval training protocol with 2 min passive recovery between sets on two different occasions in random and counterbalanced order. Each 6 min set included repeated periods of 15 s exercise interspersed with 15 s passive rest. On one occasion (RUN), all exercise periods included running at 100% of maximal aerobic speed, while on the other occasion an integrated protocol was used (INT) in which each of the two 6 min sets included 4×1.5 min periods of running exercise at 100% of maximal aerobic speed in combination with jumping (i.e., 2×15 running with 15 s rest and 1×15 s drop jumping with 15 s rest). Time spent above 85% HRmax was two-fold higher in INT compared to RUN (8.5±3.6 vs. 4.3±3.9 min, respectively,p= 0.0014). Interestingly, heart rate increased above 95% HRmaxonly in INT and almost no time was spent above 95% HRmaxin RUN (1.4±1.9 vs. 0.1±0.2 min, respectively,p= 0.008). Blood lactate concen- tration at the end of the second set of INT was higher than RUN (7.3±3.2 vs.4.6±2.7 mmol/L, p= 0.002). Countermovement jump was higher in INT after the end of second set by 6.4% (p= 0.04), 6.7%(p= 0.04),7.8% (p< 0.01)
in INT and almost no time was spent above 95% HRmaxin RUN (1.4±1.9 vs. 0.1±0.2 min, respectively,p= 0.008). Blood lactate concen- tration at the end of the second set of INT was higher than RUN (7.3±3.2 vs.4.6±2.7 mmol/L, p= 0.002). Countermovement jump was higher in INT after the end of second set by 6.4% (p= 0.04), 6.7%(p= 0.04),7.8% (p< 0.01) and 7.3% (p< 0.001), at 2, 6 and 8 min after set 2. In conclusion, the comparison between INT and RUN shows that INT not only elicits higher physiological and metabolic responses, but also acutely enhances neuromuscular performance for at least 8 min after the end of exercise. The integrated running/jumping high-intensity interval exercise approach could be a very useful and time efficient method for strength and conditioning coaches, especially in team sports, in which the time available for the improvement of physical parameters is limited. Keywords:high-intensity endurance exercise; plyometric training; neuromuscular performance; VO 2max 1. Introduction Several team sports, such as soccer and handball, require a combination of high cardiopulmonary endurance and muscle power, and thus training must target both these qualities in the limited time that is available for physical conditioning [1]. High-intensity interval exercise (HIIE) is a time-efficient method to improve aerobic fitness [2–5]. Most HIIE studies involved running, cycling or rowing exercise at intensities of around 80–100% VO2max[5–8]. However, HIIE may be further divided into short- or long-type interval exercise [2]. Short intervals consist of repeated work bouts of 10–60 s at intensities ranging from 100 to 120% VO2max. Long intervals include repeated work bouts of >60 s duration at intensities ranging from the velocity corresponding to lactate threshold or to critical power up to 100% VO2max[2]. Altering the duration of work, rest or intensity modifies the physiological, metabolic and neuromuscular responses to this type of exercise [3,4]. Interestingly, repeated jumping, instead of running, has been proposed as an effective HIIE modality to improve cardiorespiratory parameters [9,10]. In a recent study [10], an 11 min Sports2024,12, 76.
the physiological, metabolic and neuromuscular responses to this type of exercise [3,4]. Interestingly, repeated jumping, instead of running, has been proposed as an effective HIIE modality to improve cardiorespiratory parameters [9,10]. In a recent study [10], an 11 min Sports2024,12, 76.
Sports2024,12, 76 2 of 11 bout of repeated jumping (15 s work and 15 s rest) with nine drop jumps per 15 s of work, was shown to induce similar oxygen uptake responses compared with an equal duration and structure high-intensity running protocol (at 120% vVO2max). The time spent at VO2max in that study was identical in the two protocols (141 s±151 s vs. 145 s±76 s) (p= 0.92). The effectiveness of repeated jumping in inducing considerable cardiorespiratory responses has also been demonstrated in another study [11], where eight sets of 10 drop jumps, separated by 3 min of passive recovery, elevated oxygen uptake up to 83% of VO2max. Thus, it seems that high frequency jumping exercise with minimized rest periods between jumps may be adequate to increase metabolic demands, elevate oxygen uptake and increase the time spent above 90% of VO2max, which is considered to be a key factor for increasing central and peripheral responses related to improved VO2maxand endurance performance [2,4]. Several studies have suggested that training at intensities close to VO2max(i.e., 90–100% VO2max) is the most effective for enhancing VO2max[12] Consequently, there is an interest in prescribing training protocols that allow the longest time near VO2max. Since VO2and heart rate (HR) are linearly related [2], relative HR (i.e., %HRmax) may be used as a surrogate to % VO2max, because it is easily measured in a continuous fashion during exercise with minimal equipment. Indeed, several studies have prescribed HR-based training protocols (i.e., running at 90–95% HRmax) and found significant increases in VO2max[2,4]. HIIE protocols have been found to be more effective than continuous protocols for increasing time spent above 90% VO2max[13]. On the other hand, the use of plyometric exercises such as repeated jumps in a training session is also an effective way to improve the muscle power of the lower limbs, and thus jumping height, sprinting speed, change of direction and agility [14–17]. So far, all studies using repeated jumps to induce high cardiorespiratory load have used a large number of repetitions (150–200 jumps) performed either over a long duration (from 11 min to 25 min) [11,16,17]
is also an effective way to improve the muscle power of the lower limbs, and thus jumping height, sprinting speed, change of direction and agility [14–17]. So far, all studies using repeated jumps to induce high cardiorespiratory load have used a large number of repetitions (150–200 jumps) performed either over a long duration (from 11 min to 25 min) [11,16,17] or with very short or no rest intervals, which may cause excessive fatigue [9]. Also, many jumps induce high neuromuscular and joint load, and thus jumping exercise protocols should be carefully prescribed to minimize fatigue and maximize cardiorespiratory responses. Evidence from a recent study [11] suggests that a rest period of 15 s between bouts of jumping results in a good balance between fatigue and cardiorespiratory responses, compared to longer rest durations. Furthermore, a jumping frequency of 0.6 jumps per second, i.e., nine jumps in 15 s, is required to attain high cardiorespiratory responses, albeit with considerable fatigue, as evidenced by evoked potentiated quadriceps twitch measurements pre- and post-exercise [10]. In an attempt to explore whether the benefits of both high-intensity running and lower limb power training can be gained during a single protocol, the purpose of the present study was to examine the physiological responses (i.e., heart rate, blood lactate concentration) and neuromuscular performance during and following a HIIE session that integrated jumping and running exercises, with an optimized structure based on the existing evidence [11,16,17]. We hypothesized that the acute physiological responses would be the same during a running and an integrated running/jumping protocol, but lower limb power would be enhanced, rather than decreased, in the integrated running/jumping HIIE protocol. 2. Materials and Methods 2.1. Participants An a priori power analysis using repeated within-factors analysis of variance (G-Power software, v. 3.1.9.2, Universität Kiel, Kiel, Germany) indicated that a minimum sample size of 10 participants would be needed to detect a moderate effect size of 0.5, based on a power of 0.80, alpha of 0.05 and correlation coefficient of 0.5 between repeated measures. Sixteen male recreationally trained athletes (age: 20.1±2.2 years, body height:180.0±6.5 cm, body mass: 75.7±6.4 kg, VO2max:
software, v. 3.1.9.2, Universität Kiel, Kiel, Germany) indicated that a minimum sample size of 10 participants would be needed to detect a moderate effect size of 0.5, based on a power of 0.80, alpha of 0.05 and correlation coefficient of 0.5 between repeated measures. Sixteen male recreationally trained athletes (age: 20.1±2.2 years, body height:180.0±6.5 cm, body mass: 75.7±6.4 kg, VO2max: 55.8±4.3 mL/kg/min, vVO2max: 15.4±1.3 km/h) volunteered to take part in this study. Participants were amateur games players who were thoroughly familiarized with running-based HIIT formats. Before participation, all
Sports2024,12, 76 3 of 11 athletes signed an informed consent form and completed a health history questionnaire. None of them had any injuries for at least one year before the experimental sessions. Also, participants were non-smokers and did not take any medications or supplements which could affect their performance or metabolism. Players were instructed to maintain the same diet for 24 h and to avoid intense workouts for at least 48 h prior to each session. All procedures were in accordance with the Declaration of Helsinki and approved by the local university ethics committee (n.1467/11-01-23, approval date 11 January 2023). 2.2. Procedures Participants took part in one familiarization session, one preliminary measurements session and two main sessions 3–7 days apart. Before every familiarization, preliminary or main experimental session, a standardized warm up was performed, including 5 min running at 65–75% of maximum heart rate and 5 min of dynamic stretching. The familiarization session included a standardized warm-up and drop jumps from dif- ferent heights. Also, part (10 min) of the multistage aerobic shuttle run test was performed in this session. In the preliminary session, the drop jump height used in the integrated session was determined. Furthermore, VO2maxand velocity at VO2max(vVO2max) were esti- mated using the multistage shuttle run test [18] and vVO2maxwas calculated by Berthoin’s equation [19]. To determine the individual drop jump height, participants executed two jumps from each of four different heights (30 cm, 40 cm, 50 cm and 60 cm) with 1 min passive recovery between jumps and 3 min between heights with random and counterbal- anced order. Jump height was calculated from flight time, using a recent mobile app named “My Jump 2”. This application is compatible with iPhone devices (Apple, Inc., Cupertino, CA, USA) which have relatively high video sampling rates (240 fps) and have been shown to provide valid and reliable data during fast stretch shortening cycle (SSC) exercises such as drop jumps and sprints, and during slow SSC exercises such as the counter movement jump (CMJ) [20–24]. Power output was calculated using the Sayers’s equation [25]. The jump height eliciting the highest power
have relatively high video sampling rates (240 fps) and have been shown to provide valid and reliable data during fast stretch shortening cycle (SSC) exercises such as drop jumps and sprints, and during slow SSC exercises such as the counter movement jump (CMJ) [20–24]. Power output was calculated using the Sayers’s equation [25]. The jump height eliciting the highest power output was chosen as the individual optimum and was used during the main sessions. Following 15 min of rest after the drop jump test, participants performed a 20 m shuttle run test to evaluate VO2maxand vVO2maxaccording to Leger’s protocol [18]. Two main sessions were performed in a random and counterbalanced order. They both included two sets of 6 min (15 s exercise bouts interspersed with 15 s intervals of passive recovery) with a 2 min passive rest in between sets. On one occasion, all 15 s exercise bouts included running at high intensity (100% vVO2max), while on the other occasion the 15 s exercise bouts included running at the same intensity (100% vVO2max), as well as repeated jumping from the predetermined individual drop jump height. Details of this protocol are presented below. The recovery time between sessions was 3–7 days. Heart rate (HR) was measured during each main session and for 1 min into recovery after the end of the exercise, since it is an appropriate index of exercise intensity and is linearly related to oxygen consumption [2,4]. Blood lactate (BLa) was measured before and after the first and second set of each condition. Neuromuscular performance was assessed via the CMJ with the hands on the hips, before and after the first and second set, and also 2, 4, 6, 8 and 10 min after the end of each session. This study has certain limitations. To measure the level of increase in aerobic metabolism, it would have been useful to record and compare VO2during each protocol. Of course, this would require a portable device which was not available at the time of the study. Also, it would have been interesting to apply this protocol to a target population, such as
This study has certain limitations. To measure the level of increase in aerobic metabolism, it would have been useful to record and compare VO2during each protocol. Of course, this would require a portable device which was not available at the time of the study. Also, it would have been interesting to apply this protocol to a target population, such as in football players, who may use it during their weekly microcycle. Finally, the mechanisms of fatigue during and after the experimental sessions could have been examined with a more precise method, e.g., electric nerve stimulation or transcranial magnetic stimulation, instead of an indirect indicator such as CMJ height.
Sports2024,12, 76 4 of 11 2.3. Running and Integrated Sessions Prior to each main test, a standardized warm-up was undertaken, including 5 min jogging at 65–75% HRmaxfollowed by 5 min dynamic stretching. Three minutes after the end of the standardized warm-up, BLa and CMJ were measured (within one minute), and the main session started one minute later (i.e., 4 min after the end of the warm-up). The running session (RUN) included two 6 min sets of high-intensity running exercise, as illustrated in Figure. The participants had to complete 12 repetitions of running for 15 s at 100% of vVO2maxinterspersed with 15 s intervals of passive recovery [26,27]. The recovery interval between sets was 2 min.Sports 2024, 12, x FOR PEER REVIEW 4 of 11 examined with a more precise method, e.g., electric nerve stimulation or transcranial mag- netic stimulation, instead of an indirect indicator such as CMJ height. 2.3. Running and Integrated Sessions Prior to each main test, a standardized warm-up was undertaken, including 5 min jogging at 65–75% HR max followed by 5 min dynamic stretching. Three minutes after the end of the standardized warm-up, BLa and CMJ were measured (within one minute), and the main session started one minute later (i.e., 4 min after the end of the warm-up). The running session (RUN) included two 6 min sets of high-intensity running exer- cise, as illustrated in Figure 1. The participants had to complete 12 repetitions of running for 15 s at 100% of vVO 2max interspersed with 15 s intervals of passive recovery [26,27]. The recovery interval between sets was 2 min. Figure 1. Structure of the running (RUN) session. The integrated (INT) session included a combination of high-intensity running and jumping exercises of 2 × 6 min, as illustrated in Figure 2. During each 6 min set, the par- ticipants had to complete 4 consecutive rounds of 1.5 min, each including 2 bouts of 15 s running at 100% vVO 2max and one 15 s bout of jumping (9 drop jumps) from the predeter- mined height, all interspersed with 15 s of passive recovery. The drop jumping
as illustrated in Figure 2. During each 6 min set, the par- ticipants had to complete 4 consecutive rounds of 1.5 min, each including 2 bouts of 15 s running at 100% vVO 2max and one 15 s bout of jumping (9 drop jumps) from the predeter- mined height, all interspersed with 15 s of passive recovery. The drop jumping exercise was executed using two boxes of appropriate height, as shown in Figure 3. The distance between the two boxes was 1 m and a metronome was used to determine drop jump rate. Figure 2. Structure of the integrated (INT) running and jumping session. Figure 1.Structure of the running (RUN) session. The integrated (INT) session included a combination of high-intensity running and jumping exercises of 2×6 min, as illustrated in Figure. During each 6 min set, the participants had to complete 4 consecutive rounds of 1.5 min, each including 2 bouts of 15 s running at 100% vVO2maxand one 15 s bout of jumping (9 drop jumps) from the predetermined height, all interspersed with 15 s of passive recovery. The drop jumping exercise was executed using two boxes of appropriate height, as shown in Figure. The distance between the two boxes was 1 m and a metronome was used to determine drop jump rate.Sports 2024, 12, x FOR PEER REVIEW 4 of 11 examined with a more precise method, e.g., electric nerve stimulation or transcranial mag- netic stimulation, instead of an indirect indicator such as CMJ height. 2.3. Running and Integrated Sessions Prior to each main test, a standardized warm-up was undertaken, including 5 min jogging at 65–75% HR max followed by 5 min dynamic stretching. Three minutes after the end of the standardized warm-up, BLa and CMJ were measured (within one minute), and the main session started one minute later (i.e., 4 min after the end of the warm-up). The running session (RUN) included two 6 min sets of high-intensity running exer- cise, as illustrated in Figure 1. The participants had to complete 12 repetitions of running for 15 s at 100% of vVO 2max interspersed with 15 s
(within one minute), and the main session started one minute later (i.e., 4 min after the end of the warm-up). The running session (RUN) included two 6 min sets of high-intensity running exer- cise, as illustrated in Figure 1. The participants had to complete 12 repetitions of running for 15 s at 100% of vVO 2max interspersed with 15 s intervals of passive recovery [26,27]. The recovery interval between sets was 2 min. Figure 1. Structure of the running (RUN) session. The integrated (INT) session included a combination of high-intensity running and jumping exercises of 2 × 6 min, as illustrated in Figure 2. During each 6 min set, the par- ticipants had to complete 4 consecutive rounds of 1.5 min, each including 2 bouts of 15 s running at 100% vVO 2max and one 15 s bout of jumping (9 drop jumps) from the predeter- mined height, all interspersed with 15 s of passive recovery. The drop jumping exercise was executed using two boxes of appropriate height, as shown in Figure 3. The distance between the two boxes was 1 m and a metronome was used to determine drop jump rate. Figure 2. Structure of the integrated (INT) running and jumping session. Figure 2.Structure of the integrated (INT) running and jumping session.
Description
The study investigates physiological responses in athletes during integrated high-intensity interval training.