Effects of Short-Term Concurrent Training Cessation on the Energy Cost of Running and Neuromuscular Performances in Middle-Distance Runners

pports the implementation of concurrent strength and running training, within the same mesocycle, to improve performances in middle- and long-distance events. How- ever, very little is known about the effects of concurrent training cessation. The purpose of this investigation was to describe the effects of 4 weeks of explosive strength training cessation after an 8-week concurrent training protocol. Eight runners completed this study, which rst included either plyometric (n= 4) or dynamic weight training (n= 4) in addition to the usual running regimen. Explosive strength training was thereafter interrupted for 4 weeks, during which running sessions were maintained. Participants were tested at baseline, after concurrent training and after concurrent training cessation. The results suggest that the energy cost of running improvements observed after the intervention ( 5.75%; 95% CI = 8.47 to 3.03) were maintained once explosive strength training

the usual running regimen. Explosive strength training was thereafter interrupted for 4 weeks, during which running sessions were maintained. Participants were tested at baseline, after concurrent training and after concurrent training cessation. The results suggest that the energy cost of running improvements observed after the intervention ( 5.75%; 95% CI = 8.47 to 3.03) were maintained once explosive strength training was interrupted ( 6.31%; 95% CI = 10.30 to 2.32). The results also suggest that neuromuscular performances were maintained after 4 weeks of concurrent training cessation, especially when tests were speci c to the training intervention. Furthermore, a 3000m time trial revealed a similar pattern, with improvements after the concurrent mesocycle ( 2.40%; 95% CI = 4.65 to 0.16) and after concurrent training cessation ( 4.43%; 95% CI = 6.83 to 2.03). Overall, only trivial changes were observed for aerobic endurance and . VO2peak . Together, these results suggest that short-term explosive strength training cessation might be bene cial and could be considered as a taper strategy for middle-distance runners. However, coaches and athletes must interpret these results cautiously considering the study's low sample size and the very limited available literature in this domain. Keywords:strength training; running economy; detraining 1. Introduction Detraining, de ned as a partial or complete loss of training-related adaptations as a consequence of training load reduction or training cessation [1], represents a crucial factor to consider both from a sports performance perspective but also for the athletes' overall health and well-being [2]. The effects of short-term training cessation (4 weeks or less) are associated with declines in numerous tness outcomes. For instance, 3 to 4 weeks of strength training cessation could lead to signi cant reductions in force endurance, maxi- mal power and maximal force [3]. In addition to neuromuscular losses, training cessation could lead to declines in cardiovascular adaptations [1]. Twelve days of training inter- ruption led to . VO2max declines of more than 5% in well-trained cyclists [4], and aerobic Sports2021,9, 1.

In addition to neuromuscular losses, training cessation could lead to declines in cardiovascular adaptations [1]. Twelve days of training inter- ruption led to . VO2max declines of more than 5% in well-trained cyclists [4], and aerobic Sports2021,9, 1.

Sports2021,9, 1 2 of 8 endurance could be similarly affected [5]. Intriguingly, the energy cost of running (Cr) does not seem to be modi ed after short-term (2 weeks) training cessation in distance runners [6]. Cr, a crucial performance determinant in middle- and long-distance events, could be improved after strength training interventions concurrently implemented with a running program [7], provided that training variables are manipulated appropriately [8]. While a recent review reported that 2 to 4 weeks of concurrent training interruption leads to reductions in 1RM (7–10%), . VO2max (5–15%), vertical jump (3–5%) as well as agility and repeated sprint ability (1–5%) [9], much less is known about the effects of concurrent training cessation on Cr. Thus far, one study including six elite male runners showed that the improvements in Cr attained after 12 weeks of concurrent training were maintained after 5 weeks of resistance training cessation [10]. In order to add information to this very limited but nevertheless important area of research, the purpose of this case report was to describe the effects of 4 weeks of explosive strength training cessation after an 8-week concurrent training protocol. We expected that the training-related bene ts on Cr would be maintained after training cessation despite reductions in lower body maximal power. 2. Materials and Methods 2.1. Experimental Approach to the Problem This investigation is a follow-up of an intervention study published by our research team, investigating the effects of explosive strength training on the energy cost of run- ning [11]. In the original version of the study, concurrent training was followed by 4 weeks of strength training cessation, during which running sessions were maintained. Due to a major dropout rate (more than 40%) after the 1st cohort, the training cessation part was cancelled. Nonetheless, some participants from this 1st cohort completed the entire study, and their results are now presented in this case report. Brie y, participants were divided into 3 groups (plyometric training—PT, dynamic weight training—DWT or a control intervention—running only) for an 8-week concurrent training protocol, which was immediately followed by 4 weeks of explosive strength training cessation. Participants

was cancelled. Nonetheless, some participants from this 1st cohort completed the entire study, and their results are now presented in this case report. Brie y, participants were divided into 3 groups (plyometric training—PT, dynamic weight training—DWT or a control intervention—running only) for an 8-week concurrent training protocol, which was immediately followed by 4 weeks of explosive strength training cessation. Participants were therefore tested at baseline, after the concurrent training protocol and after the train- ing cessation period. This study was reviewed and approved by the Research Ethics Board at Universit²de Montr²al, where the study was conducted. All subjects were informed about the risks and bene ts of the investigation and then provided informed consent before participating in the study. 2.2. Subjects Eight participants (n= 4 for each DWT and PT) completed the entire study, in- cluding the concurrent training cessation part. However, no participants from the con- trol intervention completed the training interruption period. Participants were well- trained male runners (see Table experience in strength training. All participants had experience in different amateur running competitions.

Sports2021,9, 1 3 of 8 Table 1.Aerobic indices of running performances. Cr (kcal kg 1 km 1 ) . VO2peak (mL kg 1 min 1 ) AerEnd (%) 3000 m(s) Pre Post FU Pre Post FU Pre Post FU Pre Post FU P1 1.21 1.11 1.07 63.4 58.9 57.7 85.6 90.8 85.4 765 700 703 P2 1.15 1.06 1.07 66.9 64.9 66.0 88.6 87.3 91.9 677 669 653 P3 1.07 0.97 0.91 64.0 64.0 61.2 92.6 92.4 93.1 648 632 627 P4 1.21 1.12 1.23 56.6 55.6 61.7 88.1 86.0 85.7 791 785 764 Mean 1.16 1.06 1.07 62.7 60.9 61.7 88.7 89.1 89.0 720.3696.5 686.8 SD 0.07 0.07 0.13 4.4 4.4 3.4 2.9 3.0 4.1 68.6 65.2 60.4 ES 0.95 a 0.03 b 0.31 a 0.15 b 0.09 a 0.02 b 0.26 a 0.10 b 0.42 c 0.20 c 0.05 c 0.34 c D1 1.00 0.97 0.97 50.7 51.4 55.3 89.3 86.8 85.4 780 778 790 D2 1.02 1.04 1.02 54.1 51.9 57.3 83.3 83.1 83.8 810 812 758 D3 0.96 0.93 0.90 72.2 70.4 67.9 91.8 91.8 NA 574 560 NA D4 1.13 1.03 1.01 56.6 57.3 56.9 90.6 88.6 89.4 769 739 711 Mean 1.03 0.99 0.98 58.4 57.8 59.4 87.8 86.2 86.2 786.3776.3 753.0 SD 0.07 0.05 0.05 9.5 8.9 5.8 3.9 2.8 2.9 21.2 36.5 39.7 ES 0.38 a 0.21 b 0.05 a 0.09 b 0.16 a 0.01 b 0.13 a 0.35 b 0.55 c 0.03 c 0.24 c 0.57 c Each line (P1–P4 and D1–D4) corresponds to a participant. Cr: Energy Cost of Running, AerEnd: Aerobic Endurance, FU: Follow-Up, ES a-b-c : Effect size a—Post vs. Pre, b—FU vs. Post, c—FU vs. Pre, NA: Data non-available at FU, so participant (D3) excluded from Means, SD and ES calculations. 2.3. Testing Protocol All tests were performed at the same hour of the day, and organized into three testing sessions separated by at least 48 h, using the following sequence: (1) Cr and . VO2peak , (2) lower-body maximal power, (3) countermovement jumps (CMJ) and the 3000 m time trial. Testing at all 3 time points

SD and ES calculations. 2.3. Testing Protocol All tests were performed at the same hour of the day, and organized into three testing sessions separated by at least 48 h, using the following sequence: (1) Cr and . VO2peak , (2) lower-body maximal power, (3) countermovement jumps (CMJ) and the 3000 m time trial. Testing at all 3 time points (pre, post and follow-up) included measure- ments of key aerobic indices of running performance [12] and a 3000 m time-trial. . VO2peak (mL kg 1 min 1 ) was measured (Moxus, AEI Technologies, Naperville, IL, USA) during an incremental test until exhaustion on a treadmill (Quinton, VA, USA), which also led to the identi cation of peak treadmill speed (PTS). Aerobic endurance represented the ratio (%) between the average speed maintained during the 3000 m time-trial and PTS [13]. The 3000 m time-trial was performed on a 200 m indoor track. Furthermore, lower body neuromuscular performances were assessed. A force-velocity squat test was completed on a guided rack and maximal power (W) was measured using a linear encoder (MuscleLab, Ergotest, Langesund, Norway). Vertical jump height (cm) was measured with an optical system (Optojump, Microgate, Bolzano, Italy) during a CMJ. Body mass index (kg/m 2 ) was also measured at each time point. 2.4. Training Protocol During the concurrent training period, PT and DWT participants included 1 ex- plosive strength training session weekly in addition to their normal running regimen. Strength training load was equivalent for both experimental groups with 3 to 6 sets of 8 repetitions completed during each session. While PT participants executed drop jumps with a starting box height that optimized vertical jump performance, the DWT protocol consisted of concentric-only jumps with a load that optimized power output. Feedback was provided after each repetition to control intensity as the objective was to achieve 95% of peak performance for each repetition (peak power established during a force-velocity test for DWT; maximal vertical jump height for PT). The running program, equivalent between experimental groups [11], included 3 weekly sessions, with an emphasis on (1) maximal aerobic speed, (2) intermittent aerobic

Feedback was provided after each repetition to control intensity as the objective was to achieve 95% of peak performance for each repetition (peak power established during a force-velocity test for DWT; maximal vertical jump height for PT). The running program, equivalent between experimental groups [11], included 3 weekly sessions, with an emphasis on (1) maximal aerobic speed, (2) intermittent aerobic endurance and (3) continuous aerobic endurance. All training sessions were separated by at least 24 h.

Sports2021,9, 1 4 of 8 2.5. Statistical Analyses Considering the small sample size, a descriptive approach was prioritized. First, all in- dividual scores were reported. Effect sizes (Hedges' g) were calculated as described previously [14] using absolute scores for the entire sample (n= 8) but also for each training intervention. Interpretation was based on Cohen's scale [15] where the effect was consid- ered trivial (g < 0.20), small (0.20 g < 0.50), moderate (0.50 g < 0.79), or large (g 0.80). Moreover, individual relative changes (RC) from pre- to post concurrent training and from pre to follow-up were calculated ((post-pre)/pre * 100). Con dence intervals (95% CI) were then computed based on these relative changes. Cr changes were interpreted considering the smallest detectable difference ( = 2%) as well as the typical adaptations observed after concurrent training interventions (2–8%) [7]. 3. Results Analyses for the entire sample (n= 8) revealed that Cr was moderately improved from pre to post concurrent training (g = 0.57; RC (95% CI) = 5.75 ( 8.47 to 3.03)) and these changes were maintained after the 4-week cessation period as suggested by a moderate pre to follow-up effect size (g = 0.61; RC (95% CI) = 6.31% ( 10.30 to 2.32)). When focusing on the training modality (Table), PT resulted in large Cr reductions (g = 0.95 ; RC (95% CI) = 8.18% ( 8.97 to 7.38)) whereas effects were considered small for DWT (g = 0.38; RC (95% CI) = 3.33% ( 7.68 to 1.02)). From pre to follow-up, reductions were considered small for PT (g = 0.42; RC (95% CI) = 7.84% ( 15.82 to 0.13)) and moderate for DWT (g = 0.55; RC (95% CI) = 4.78% ( 10.01 to 0.45)). Figure shows that seven runners improved Cr by at least 2% after the 8-week concurrent training intervention. From pre to follow-up, six runners had scores that were at least 2% lower (indication of improvements) than during baseline testing.Sports 2020, 8, x FOR PEER REVIEW 5 of 8 Figure 1. Individual % changes in energy cost of running. Plyometric training: solid lines. Dynamic

that seven runners improved Cr by at least 2% after the 8-week concurrent training intervention. From pre to follow-up, six runners had scores that were at least 2% lower (indication of improvements) than during baseline testing.Sports 2020, 8, x FOR PEER REVIEW 5 of 8 Figure 1. Individual % changes in energy cost of running. Plyometric training: solid lines. Dynamic weight training: dashed lines. Table 2. Anthropometry and neuromuscular performances. Age (Years) BMI (kg/m 2 ) Maximal Power (W) CMJ (cm) Pre Post FU Pre Post FU Pre Post FU PT P1 22 24.0 24.2 23.7 1446.2 1296.2 1266.8 39.1 40.1 41.8 P2 23 20.0 20.5 20.2 985.7 1222.7 1095.6 36.7 41.0 38.4 P3 24 24.4 23.5 23.5 979.9 835.9 852.4 29.7 31.9 31.9 P4 39 26.3 25.5 25.5 1223.0 1174.5 1081.3 26.8 31.1 31.1 Mean 32.0 23.7 23.4 23.2 1158.7 1132.3 1074.0 33.1 36.0 35.8 SD 11.2 2.6 2.1 2.2 222.6 203.9 170.1 5.8 5.3 5.2 ES −0.05 a −0.06 b −0.09 a −0.19 b 0.37 a −0.03 b −0.07 c −0.29 c 0.30 c DWT D1 37 24.1 24.5 24.1 968.6 1201.8 1206.9 27.4 29.0 30.4 D2 27 27.7 25.7 25.0 1359.7 1446.9 1414.4 35.9 41.0 38.3 D3 35 21.2 21.2 21.2 1012.1 1168.8 1147.5 37.6 39.3 NA D4 33 24.7 24.4 24.2 1373.0 1687.0 1694.7 41.0 43.5 41.8 Mean 33.0 24.4 23.9 23.6 1178.4 1376.1 1365.9 34.8 37.8 36.8 SD 4.3 2.7 1.9 1.7 217.9 241.5 247.3 6.9 7.8 5.8 ES −0.11 a −0.07 b 0.61 a −0.03 b 0.27 a −0.04 b −0.17 c 0.57 c 0.08 c -16.00 -14.00 -12.00 -10.00 -8.00 -6.00 -4.00 -2.00 0.00 2.00 4.00 Pre to Post Pre to Follow Up % Changes Figure 1. Individual % changes in energy cost of running. Plyometric training: solid lines. Dynamic weight training: dashed lines.

Sports2021,9, 1 5 of 8 Small improvements in maximal power assessed during the force-velocity test were found after the 8-week concurrent training protocol (g = 0.33; RC (95% CI) = 7.98% ( 3.10 to 19.07)). These changes were maintained after training cessation, as indicated by a small pre to follow-up effect size (g = 0.20; RC (95% CI) = 4.95% ( 5.96 to 15.86)). How- ever, speci c training effects were observed. Indeed, as shown in Table, DWT led to moderate improvements both from pre to post (g = 0.61; RC (95% CI) = 17.21% (9.23 to 25.19)) and from pre to follow-up (g = 0.57; RC (95% CI) = 16.36% (6.91 to 25.81)). For PT, trivial changes were observed from pre to post (g = 0.09; RC (95% CI) = 1.25% ( 18.33 to 15.83)), while small declines were found from pre to follow-up (g = 0.29; RC (95% CI) = 6.46% ( 17.98 to 5.06)). Table 2.Anthropometry and neuromuscular performances. Age (Years) BMI (kg/m 2 ) Maximal Power (W) CMJ (cm) Pre Post FU Pre Post FU Pre Post FU PT P1 22 24.0 24.2 23.7 1446.2 1296.2 1266.8 39.1 40.1 41.8 P2 23 20.0 20.5 20.2 985.7 1222.7 1095.6 36.7 41.0 38.4 P3 24 24.4 23.5 23.5 979.9 835.9 852.4 29.7 31.9 31.9 P4 39 26.3 25.5 25.5 1223.0 1174.5 1081.3 26.8 31.1 31.1 Mean 32.0 23.7 23.4 23.2 1158.7 1132.3 1074.0 33.1 36.0 35.8 SD 11.2 2.6 2.1 2.2 222.6 203.9 170.1 5.8 5.3 5.2 ES 0.05 a 0.06 b 0.09 a 0.19 b 0.37 a 0.03 b 0.07 c 0.29 c 0.30 c DWT D1 37 24.1 24.5 24.1 968.6 1201.8 1206.9 27.4 29.0 30.4 D2 27 27.7 25.7 25.0 1359.7 1446.9 1414.4 35.9 41.0 38.3 D3 35 21.2 21.2 21.2 1012.1 1168.8 1147.5 37.6 39.3 NA D4 33 24.7 24.4 24.2 1373.0 1687.0 1694.7 41.0 43.5 41.8 Mean 33.0 24.4 23.9 23.6 1178.4 1376.1 1365.9 34.8 37.8 36.8 SD 4.3 2.7 1.9 1.7 217.9 241.5 247.3 6.9 7.8 5.8 ES 0.11 a 0.07 b 0.61 a 0.03 b 0.27 a 0.04 b 0.17 c

38.3 D3 35 21.2 21.2 21.2 1012.1 1168.8 1147.5 37.6 39.3 NA D4 33 24.7 24.4 24.2 1373.0 1687.0 1694.7 41.0 43.5 41.8 Mean 33.0 24.4 23.9 23.6 1178.4 1376.1 1365.9 34.8 37.8 36.8 SD 4.3 2.7 1.9 1.7 217.9 241.5 247.3 6.9 7.8 5.8 ES 0.11 a 0.07 b 0.61 a 0.03 b 0.27 a 0.04 b 0.17 c 0.57 c 0.08 c Each line (P1–P4 and D1–D4) corresponds to a participant. BMI: Body Mass Index, CMJ: countermovement jump, FU: follow-up, ES a-b-c : effect size a—post vs. pre, b—FU vs. post, c—FU vs. pre, NA: data non-available at FU, so participant (D3) excluded from means, SD and ES calculations. Similarly, small improvements in CMJ performance were found from pre to post concurrent training (g = 0.46; RC (95% CI) = 9.12% (5.46 to 12.78)) and from pre to follow-up (g = 0.28; RC (95% CI) = 7.80% (4.42 to 11.17)). When analyses were made based on the training intervention, DWT led to small and trivial changes from pre to post (g = 0.27; RC (95% CI) = 8.71% (3.33 to 14.10)) and from pre to follow-up (g = 0.08; RC (95% CI) = 6.53% (1.44 to 11.62)), respectively. Moreover, PT resulted in small improvements for both pre to post (g = 0.37; RC (95% CI) = 9.43% (3.77 to 15.10)) and pre to follow-up (g = 0.30; RC (95% CI) = 8.75% (3.84 to 13.66)). Overall (n= 8), only trivial changes (g < 0.20) were observed for other performance variables ( . VO2peak , aerobic endurance) in both pre to post and pre to follow-up compar- isons. PT participants showed small reductions in . VO2peak from pre to post (g = 0.31) as well as from pre to follow-up (g = 0.20). However, small improvements were observed for the 3000 m performance test (see Figure) after concurrent training (g = 0.24; RC [95% CI] = 2.40% [ 4.65 to 0.16]) and also after strength training cessation (i.e., pre to follow-up; g = 0.48; RC [95% CI] = 4.43% [ 6.83 to 2.03]).

This study investigates the effects of 4 weeks of explosive strength training cessation after an 8-week concurrent training protocol.