The off-season in soccer: the consequences of detraining and how to reverse them￼
The off-season in soccer is increasingly characterized by individualized training to the soccer player. Clemente et al. (2021) wanted to know whether such supplementary training can help to mitigate the effects of detraining during holidays in the off-season period.
The off-season is often characterized by a decrease in training load, a complete stop of training or an individualized exercise program with lower volumes, which takes place in the period between competitions, usually the summer period (Silva JR et al 2016). Significant decreases in training volume, intensity, and frequency during the off-season can lead to detraining and have potentially detrimental effects on performance and body composition (Suarez-Arrones L et al 2019; Requena et al. 2017).
It should be noted that detraining can occur not only in the off-season but also during the in-season winter break (Rodriguez-Fernandez A et al 2018). Although the off-season schedule varies from country to country, it generally lasts 4 to 6 weeks (Vassilis S et al. 2019), whereas the in-season break may last 2 weeks.
Both types of periods produce changes in fitness levels, due to the decrease in training stimulus, that are reversible when training is resumed.
It has been reported in the scientific literature that both, cardiovascular endurance levels and body composition, are affected by detraining during the off-season (muscle mass is lost, body fat is gained, time to complete a sprint is increased, muscle power is decreased, etc.) (Clemente F et al. 2021).
Although the off-season should include a period of rest for the player (perhaps more related to the decrease in the volume of the training, trying to maintain the intensity of the same, as if it were a tapering), it also has to be considered as a time to restart training. Especially, with individualized training, in order to adjust the level of physical fitness of the player to the minimum necessary to cope with the loads that will occur during the pre-season (taking into account that pre-seasons generate a large initial impact of load on the players due to abrupt increases in both the volume and intensity of training), where changes in the training load occur suddenly and can be dangerous for players, particularly in cases of low physical condition (as is the case of the detraining produced by off-season) (Jaspers, S et al 2017).
It has been suggested that maintaining good fitness levels can moderate peak loads (which naturally occur during the pre-season), thus decreasing the likelihood of injury (Malone,S et al. 2017).
In that sense, knowing how the off-season affects physical capacities can help to control the return to training by attending to the qualities that suffer greater deterioration for progressive programming of training.
A systematic review explains how the cessation of training affects capabilities during off-season.
For this, the group of Clemente F.M et al. (2021) conducted a systematic review and meta-analysis of how the off-season (with and without training during this) affected the physical qualities and physiological profile of the soccer player.
The authors included in the review those studies that had at least a 2-week cessation of the training period, those studies were conducted in healthy soccer players without the restriction of age or a competitive level, and they took place in the off-season. In addition, the variables to be measured were fat percentage (%), maximal oxygen consumption (VO2max ml/kg/min), distance in the yo-yo intermittent test (meters), sprint time (seconds), countermovement jump (cm), and sprint repetition ability (total time in seconds).
The results show that, for oxygen consumption, the cessation of training decreases the capacity between -3.4 and -21.2% if the activity is completely suspended. Whereas, for professional soccer players who maintained a certain degree of physical activity (OTP, off-season training program) only their aerobic profile decreased between -0.8% and -4.3%. The authors attribute this to low volumes at intensities of 50-60% of heart rate.
For the Yo-Yo intermittent test values, those who stopped training decreased between -14.8 and -22.6%, but if they had remained active this variable was not affected.
The changes in body composition during cessation of training were to be expected due to the relationship between muscle mass and adipose tissue, which increases the percentage of fat.
For the group that stopped training completely, there were incremental changes between 0.7 and 10.3%, while following an OTP did not ensure that weight was kept at bay as it also increased between 1 and 18.3%. The authors attribute these increases to changes in lifestyle habits during the off-season.
In relation to the countermovement jump, the results show a significant decrease in power values both for inactive players and for those who underwent a training program. These results showed a decrease of between -2.1 and -6.3%. Power is one of the abilities most affected, authors attribute these results to the type of program since most of the OTPs were either running work at moderate intensity or a combination of running and strength exercises at low speed and moderate intensity.
Therefore, a lack of lower body power stimulus could explain the detrimental effects of cessation of training and OTP. In that sense, OTPs should incorporate adequate neuromuscular stimulus to reduce the effect of DT on the countermovement jump (Maio Alves J, et al 2010).
Finally, the results on sprint time show a detrimental effect of both strategies, the transitional period will increase the time to complete a sprint by 2.4 to 3.3%. The authors attribute this increase in time to the fact that improvement in sprinting requires an appropriate stimulus based on high-speed training. The OTP could benefit from improvements by adding: sprint training at specific distances, sprinting at near maximal speed (>90%), and combined interventions with strength and power training.
In addition, the authors highlight the heterogeneity of both the sample and the OTP strategies as one of the limitations. In an in-depth analysis of the studies, the authors highlight that the studies that avoided DT or even improved capacities were those using high frequencies with high-intensity methods.
What strategies should be implemented to maintain capacities in off-season.
In order to maintain capacities and standardize minimum conditioning levels for the beginning of the new season, indoor training (weight room training) should be taken into account. Stimulate the strength, power, and plyometrics capacity, which in general do not have so much prominence during the season, should be the core of the work during the off-season. Sprint and sprint repeat ability training that continues during the season should also be maintained. Also, some form of cardiovascular training should be implemented to try to avoid a severe drop in capacity (possibly one HIIT workout per week).
In this regard, the NSCA has come out with positioning for training in the off-season and return to competition. Where they establish the FIT rule (Frequency, Intensity relative to volume, Rest time between intervals; to minimize the probability of muscle damage) (Caterisano, A. et al. 2019).
- Training frequency is defined as the number of sessions completed per week for a specific muscle group or type of movement (McMaster et al 2013). Programming should meet the criteria for how to distribute the exercises in training to meet the frequency parameters. It is recommended that the frequency not exceed 3 days per week per movement in the first week after cessation and not exceed 4 days in the second week.
- Intensity Relative to Volume (IRV) is a derivative of total volume including percentages of 1RM (95,107,138) and is calculated with the following equation: Sets x Repetitions x %1RM as a decimal = to IRV units. Programming allows the variable of sets, repetitions, and %RM to be modulated to meet the IRV units. A review by McMaster et al. (2013) indicates that IRV units between 11 and 20 provide the greatest strength gains, while between 21 and 30 produce strength gains but to a lesser extent, and below 11 are not adequate for strength gains. The NSCA Committee recommends an IRV between 11 and 30 per muscle or movement. IRVs above 30 are contraindicated in the two weeks following a period of inactivity.
- Rest time between intervals, also referred to as work-to-rest ratio (W:R), is a vital variable to decrease the risk of rhabdomyolysis, which is due to high volume training or hybrid workouts that mix circuit strength training with sprinting. In most cases of rhabdomyolysis the W:R was 1:1. Rest time is necessary for the cardiovascular system to supply oxygen to the muscles and reduce potential muscle damage. Consequently, the NSCA recommends in the first week of gym sessions a W:R ratio of 1:4 the first week and 1:3 the second week. The table summarizes these rules.
Retraining is especially effective to recover strength and muscle hypertrophy due to the evidence that muscle myonuclei are maintained even after extreme atrophy, which allows a return to better adaptation (what was previously understood as muscle memory) (Gunderson, et al. 2016).
For this retraining, two weeks of transition where the load is progressively increased to recover the strength values and capacities lost after inactivity would be worthwhile. What the authors of the NSCA position recommend is to start with a 50% volume (compared to seasonal values) the first week with a W:R of 1:4, to progress to 30% volume the second week with a W:R of 1:3, a 20% reduction in volume the third week and a 10% reduction the fourth week.
Applying the FIT rule to plyometric exercises is more complicated due to the differences in weight and relative strength levels of the athletes, but an estimate could be obtained using the 50/30/20/10 rule. For example, based on the recommendations of 120-140 contacts during the season, 70 contacts should not be exceeded in the first week, 100 contacts in the second week, for the average athlete. These parameters should be modified for athletes with high body mass or low relative strength levels. The average athlete could resume normal volumes in weeks 3 and 4 while athletes needing more care should continue with a 20 and 10% reduction in those weeks.
The authors also recommend, as did the authors of the off-season review, that an assessment of physical capabilities to establish the players’ fitness profile at the return to training is essential for two reasons: first, because it is an ideal time when the effects of training will not influence the player’s condition and because it is a starting point on which to build a process of evolution of the player’s physical capabilities.
In this sense, thermography from the first image can inform us of the physiological state of the player. From the first shot, it allows to establish basal profiles of the players and to report injuries or old regeneration processes, using the metric of thermal asymmetries. In addition, correlations can be made with other tests such as the Yo-Yo intermittent test, the RSA, or the sprint test to assess which absolute temperature profiles are more related to players oriented to power or cardiovascular endurance.
The detrimental effects on the player’s body composition and conditioning status that occur during the cessation of training in the off-season could be cushioned by individualized training during this period, especially for oxygen consumption values and repeat exertion at high intensity.
Analyzing the capacities by means of an evaluation (as thermography) is interesting to know the physiological state of the athlete.
Future lines of research should assess what is the minimum effective dose of this individualized program to maintain the qualities during the off-season and what are the consequences in the medium and long term during the season to carry out specific work. In addition, this specific work should focus on those abilities that later during the season do not have so much space for work and promote healthy lifestyle habits.
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