1 EFFECTS OF TAPERING ON PHYSICAL MATCH PERFORMANCE IN

1

Abstract

This study aimed to examine: i) the effect of decreasing training load (TL) during taper weeks on the physical match activities in professional soccer players, and ii) to disclose the relationship between the weekly TL and physical match activities. Rating of perceived exertion was collected after each training session and match to quantify the TL in 19 professional players over 17 standard and 7 taper weeks during the season. Physical match activities were quantified by a computerised match analysis system and compared between standard training and taper weeks. Compared to standard weeks, the duration and frequency of training sessions during the taper weeks decreased (-21.7% and -18.8%, respectively; P<0.01) with no change in intensity (-4.8%; P=0.09). Consequently, the weekly TL decreased during the taper weeks (-25.5%; P<0.01). Increases in distance covered by intense running (+15.1%; P<0.05), high-intensity running (HIR) (+15.7%; P<0.01), number of sprints (+17.8%; P<0.05) and number of high-speed runs (+15.7%; P<0.05) were observed during the seven matches played after the taper weeks. High relationships were observed between TL and HIR distance covered, number of HIR, and number of sprints (r=-0.53; r=-0.55; r=-0.65, respectively; P<0.01). Decreasing TL during taper weeks by reducing training duration and frequency but maintaining intensity was associated with an improvement in physical performance during matches. However, we cannot discount other factors such as tactical, technical and mental, also playing a role in altering match performance.

Keywords: Periodisation, training load, computerised analysis system, physical activities

Methods

Participants

Nineteen male professional soccer players who represented the same team in the Qatar Stars League (age: 25.7 ± 2.6 years; body mass: 74.1 ± 9.1 kg; height: 186.2 ± 7.1 cm; % body fat: 10.9 ± 2.5 %; professional career: 7.3 ± 2.9 years) gave consent to take part in this study. The study was approved by the local Ethics Committee in accordance with the principals outlined in the Declaration of Helsinki (2008).

Design

Training and match data were collected over a 26-week period during the 2013-2014 season. To quantify player TL, RPE was collected 30-min after each training session. Physical match activities were quantified using a computerised match analysis system. Out of the 26-weeks studied, 24-weeks were available with one competitive match and used for analysis. For each week, TL and match activities data on players who did not participate in all training sessions or completed the full match were excluded from the analysis. Goalkeepers were also excluded from the analysis.

Weekly programming

The training program was designed by the soccer club’s technical/coaching staff with no input from the study research team. Weeks were divided into standard and taper weeks according to the TL accomplished by the players. During a standard week, the players completed 6-7 training sessions in 6-days. During the taper weeks, TL was decreased by reducing the duration of each training session and the training frequency. The players participated in 5 training sessions within 6-days. The taper week represented the last week of a 3-4 week mesocycle, which was planned based on the schedule and match importance. During both the standard and taper weeks, the players participated in active recovery training the day following a match, before being given a day off (Aughey, Elias, Esmaeili, Lazarus, & Stewart, 2015; Coutts et al., 2008; Jeong et al., 2011).

Training load monitoring

RPE was collected 30-min after each training session (Impellizzeri et al., 2004) using a modified 10-point Borg scale (Borg, Hassmen, & Lagerström, 1987). Each player was asked “How did you perceive your exertion during training?” to record a subjective estimation of the physiological load during each training session. The training load was then calculated by multiplying RPE by the duration of the session in minutes. The weekly TL was calculated using the sum of the TL for all training sessions performed in a given week (Impellizzeri et al., 2004). The weekly training monotony, which is a measure of day-to-day training variability, was calculated from the average weekly TL divided by the standard deviation of the weekly TL (Foster, 1998). The weekly training strain, which is useful for monitoring training when players are undertaking high TLs, was calculated as the product of the weekly TL and weekly training monotony (Foster, 1998).

Physical match activities

A computerised, semi-automated multi-camera image recognition system (ProZone Sports Ltd^®, Version 3.0 Leeds, UK) was used to quantify physical match activities as previously described (Di Salvo, Collins, McNeill, & Cardinale, 2006; Di Salvo et al., 2009). Match running distance for each player was divided into the following zones, which are pre-categorised in the Prozone analysis system:

• Low-intensity running (LIR): running distance covered with a speed <14.4 km.h^-1;

• Intense running (IR): running distance covered with a speed ≥14.4 and <19.8 km·h^-1;

• High-speed running (HSR): running distance covered with a speed ≥19.8 and <25.2 km.h^-1;

• Sprinting: running distance covered with a speed ≥25.2 km.h^-1;

• High-intensity running (HIR): the sum of HSR and sprinting distance;

• Total distance: the sum of all distances covered during the match;

• The number of HSR actions, sprints, and HIR actions;

• Recovery time (RT): the average time elapsed between HIR actions.

Statistical analyses

All data are presented as a mean ± standard deviations (SD). Data normality was checked and verified by the Kolmogorov–Smirnov test. Independent samples t-tests were used to compare mean differences in TL and physical match activities between the standard and taper weeks. Estimates of effect size (d) were calculated for each outcome using the ratio of the mean difference to the pooled standard deviation, to quantify the magnitude of change between the standard and taper weeks. The magnitude of d was interpreted as: trivial (< 0.2); small (≥ 0.2-0.6); moderate (≥ 0.6-1.2); large (≥ 1.2-2.0) and very large (≥ 2.0) (Batterham & Hopkins, 2006). Pearson’s product moment correlation coefficients were used to examine the relationships between the weekly TL and physical match activities for each week during the season. The magnitude of the correlation was interpreted as: trivial: r < 0.1; low: 0.1-0.3; moderate: 0.3-0.5; high: 0.5-0.7; very high: 0.7-0.9; nearly perfect > 0.9; and perfect: 1 (Hopkins, 2000). All statistical analyses were conducted using the statistical package for the social sciences (SPSS, version 18.0, SPSS Inc, Chicago, IL, USA). The level of significance was set at P < 0.05. Confidence intervals (95%) are provided for mean differences and Pearson’s correlations.

Results

Overall, 160 training sessions were completed by players who participated in all training sessions and completed full matches during 24-weeks. Of the 24-weeks, this included 17 standard and 7 taper weeks to be included in the final analysis. The mean training frequency, duration, RPE, TL, monotony and strain during the standard and taper weeks are presented in Table I. Frequency and duration of the training sessions were decreased in taper weeks by 18.8% and 21.7%, respectively (P < 0.01). However, training intensity as measured using RPE, was not different between the standard and taper weeks (4.8%, P = 0.09). The TL was decreased in the taper week by 25.5% (P < 0.01). Monotony and strain of training were decreased in taper weeks by 7.8% (P = 0.23) and 35.3% (P < 0.01), respectively.

****Table I near here****

Physical match activities data during the matches after standard and taper weeks are shown in Table II. Distance covered using LIR was not different (8.3%, P = 0.09) between the taper and standard weeks. However, improvements were observed for the total running distance (10.1%, P < 0.05), IR distance (15.1%, P < 0.05), HIR distance (15.7%, P < 0.01) and the number of intense activities (HSR: 15.7%, P < 0.01; HIR: 15.7%, P < 0.01 and sprints: 17.8%, P < 0.05) during match play after the taper week. There was no difference in RT (10.1%, P = 0.26) following the taper weeks.

****Table II near here****

Weekly TL had a high negative correlation with HIR covered distance (r =-0.53, CI: 0.23–0.76, P<0.01; Figure 1a), number of sprints (r =-0.65, CI:0.32–0.84, P<0.01; Figure 1b), number of HIR (r =-0.55, CI: 0.41–0.84, P<0.01; Figure 1c) and HSR (r =-0.49, CI: 0.29–0.76, P<0.05; Figure 1d). No significant relationships were observed between the weekly TL and LIR, IR or total covered distance (r = -0.09, P=0.66; r =-0.14, P=0.51; r =-0.17, P=0.43; respectively).

****Figure 1 near here****

Discussion

The present study was undertaken to examine the effect of decreasing TL during taper weeks compared with standard weeks on physical match activities in professional soccer players. We found: 1) compared to a standard training week, taper weeks had a reduced TL brought about by decreasing the duration and frequency of training, while training intensity was maintained; 2) improvements in running distance covered and number of intense activities during matches played after taper weeks; and 3) high negative correlations between weekly TL and high-intensity/sprint match activities over the season.

Our results showed a very large reduction in the players’ TL (d > 2) during the taper weeks compared to standard weeks. Mean frequency and duration of training sessions was moderately and very largely decreased in the taper weeks (d >0.6 and d >2; respectively), with a moderate but not significant decline in training intensity (d >0.6). This suggests that the TL during the taper weeks was reduced due to a reduction in the frequency and duration of the training sessions, whereas the training intensity was maintained. Previously, Bosquet et al. (2007) reported that the performance improvement after a taper was more sensitive to a reduction in training duration and frequency. Indeed, it has been suggested that TL should not be reduced at the expense of training intensity, which is regarded as a key parameter for eliciting training related adaptations during the taper (Mujika et al., 2004). Alongside the decline in TL, a moderate (d > 0.6) and very large (d > 1.2) decline in training monotony and strain were noted in taper weeks, respectively. Training monotony is related to the onset of overtraining when monotonous training is combined with high TL (Foster, 1998) and high levels of training strain are usually reached during the preparation period of training (Coutts et al., 2008). It has been suggested that training with lower monotony and strain may prevent injury, illness and improve performance (Coutts et al., 2008; Foster, 1998). However, the decrease in monotony and strain could reduce injury and improve performance, which is a major goal of tapering. Previously, it has been shown that low monotony and strain is associated with the winning team in elite Australian football (Aughey et al., 2015).

To the best of our knowledge, this the first study to investigate tapering on match performance in professional soccer players. However, the results from this study need to be viewed in the light that soccer performance is highly complex (Bangsbo et al., 2006; Coutts et al., 2008) and numerous factors may that could explain changes in physical activities and influence match physical activities and running performance (Bradley & Noakes, 2013; Di Salvo et al., 2009; Lago, 2009) which were not reported in the current study. Despite this caveat, the present study found a moderate (d > 0.6) increase in total distance covered, LIR, and IR during matches following a taper week. Likewise, a trivial (d < 0.2) increase of number of HSR and a large (d ≥ 0.6) increase in HIR covered distance, numbers of sprints and number of HIR were also observed during the match played after the taper weeks. In conjunction with the improvements in match running performance after a taper week, a moderate (d > 0.6) reduction in RT, although not significant, was observed. Improved match physical performance after taper weeks could be also attributed to the effect of reduced TL. Our results are in agreement with researchers reporting improvements in aerobic performance in individual sports (Bosquet et al., 2007; Mujika & Padilla, 2003), high-intensity performance in rugby players during pre-season training (Coutts et al., 2007; Elloumi et al., 2012) and both aerobic and high-intensity performance in simulated laboratory team sport activity (Slattery et al., 2012) following a taper period. Elloumi et al. (2012) showed improvements in 10, 20 and 30-m sprint (2–3%) performance after a 14-day taper in rugby players. Similarly, Coutts et al. (2007) demonstrated significant increases in 10-m sprint (2%) and jump (5%) performance using a 7-day taper in rugby players. Finally, Slattery et al. (2012) showed significant improvements in sprint performances in laboratory simulated team sport activity after 4-day of reducing TL. To the authors’ knowledge, the present data represents the first attempt to examine the effects of tapering on match running performance in soccer players.

The percentage improvement in physical performance after a taper week will be greater when TLs are accumulated during previous pre-taper weeks where the training cycle is characterised by intense training and a high TL (Bosquet et al., 2007; Mujika & Padilla, 2003). This finding as well as ours may be explained by a number of physiological changes that may occur during tapering. It has been reported that tapering can cause hypervolemia and improve red cell production (Neary, Martin, & Quinney, 2003; Shepley et al., 1992) and increase oxidative enzyme activity (Neary et al., 2003; Shepley et al., 1992) which may contribute to an increase in oxygen extraction. Moreover, the tapering has been shown to increase muscle strength and power by: (i) reducing muscle damage; (ii) increasing anabolism, and (iii) increasing muscle glycogen stores (Coutts et al., 2007). Certainly, the increase in muscle glycogen and aerobic enzyme activity are crucial to improve repeated-sprint performance in soccer players (Rico-Sanz, Zehnder, Buchli, Dambach, & Boutellier, 1999). Improvement in physical activities during a game could also be due to the change in psychophysical parameters associated with the taper. Elloumi et al. (2012) demonstrated a reduction in training stress and fatigue during a taper period compared to an intense training period in rugby players. Similarly, Couts and Reaburn (2008) reported a decrease in perceived fatigue and general stress during a 7-day taper compared to 6-weeks of intensive training in rugby players.

The significant relationships found between weekly TL achieved by the players throughout the season and HIR covered distance, number of sprints, HSR and HIR suggest that the physical match activities of soccer players are influenced by the TL accomplished during weekly training. Our findings corroborate with Bangsbo et al. (2006) suggesting that improvements in the physical performance of elite soccer players is largely depend on TL. It has been reported that successful game actions with a ball (e.g. passes, dribbling, shots) are related to high-intensity activities (Sarmento et al., 2014). Moreover, the players of more successful teams covered greater total distance with the ball, had a high average of goals for total shots on target, performed more involvements with the ball, higher number of passes, tackles, dribbling and shots on target when compared with less successful teams (Sarmento et al., 2014).

The novel finding in the current study is that physical performance profiles during matches were enhanced after a taper week in professional soccer players. However, caution is advised when interpreting the findings from the current study as only the effect of TL was used to relate to changes in physical performance during matches. From a practical point of view, coaches are urged to schedule the taper according to the matches’ objectives and to the previous TL already accomplished by the players to improve physical performances and prevent overtraining and injury. The taper in the current study was achieved by reducing the frequency and duration of training sessions and maintaining training intensity. Thus, sports scientists and , strength and conditioning coaches should design taper week by reducing frequency and duration of training and preserving intensity to optimise physical match activities performance. Interestingly, the ~ 25.5% reductions in TL in the current study is lower than that recommended for individuals sports (~ 50%) to realise to beneficial effects of the taper (Mujika & Padilla, 2003). It will be interesting in the future to explore how tapering strategies in soccer can be optimised in terms of altering duration, frequency and intensity, and the effect of duration of pre-taper weeks and taper location to optimise performance. The lack of additional biological and psychological measurements is a limitation of the present study, but this was not possible given difficulties accessing professional soccer players during the season. If feasible, future work should investigate biological (e.g., blood or saliva samples) and psychological parameters in order to better understand the effect of TL variability in professional soccer players. Further studies are warranted to investigate the effect of tapering on other factors confounding physical performances during the matches played, such as technical abilities, tactical changes, effects of score line, playing formation, and standard of opposition in soccer players.

Conclusion

Decreasing TL by ~25% during taper weeks through a reduction in the duration and frequency of training but maintaining training intensity was associated with a 15% improvement in intense and high-intensity activities during matches in professional soccer players. Thus, oOur findings suggest taper weeks are important at improving physical performances during the matches compared with standard weeks in professional soccer players. However, in addition to the physical parameters documented in the current study, tactical, technical and mental factors should be taken into consideration in future work.

Acknowledgments

No external financial support was received for this study. The authors would like to thank all of the participants and their coaches for their understanding and availability in the completion of this study.

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Figure legend

Figure 1. Relationships between team weekly TL and high-intensity running covered distance (a), number of sprints (b), number of high-intensity running (c) and number of high-speed running (d) performed during match throughout the season (24-weeks).

Figure 1

Table I. Mean values (±SD) of weekly training load accomplished by players during standard (n= 17) and taper (n= 7) weeks.

Parameters	Standard week	Taper week	Mean difference (CI)	d
Frequency	5.9±0.7	5**	0.9 (0.4–1.4)	1.1
Duration (min)	497.3±50.4	408.5±15.4**	88.8 (48.1–129.5)	2.9
RPE	3.3±0.2	3.1±0.2NS	0.1 (0.1–0.3)	0.8
Training load	1791.4±167.2	1427.0±94.9**	364.4 (223.8–505.1)	2.5
Monotony	1.3±0.2	1.2±0.2NS	0.1 (0.1–0.2)	0.9
Strain	2306.9±433.8	1705.5±284.4**	601.3 (230.1–972.7)	1.5

CI: 95% confidence intervals for differences in means; d: Ccohen’s d for the paired sample t-test; RPE: rating of perceived exertion; ^** Mean significant difference (P < 0.01); ^NS No significant difference.