BRINGING SCIENCE TO TREATMENT

It’s all about intensity: maintaining training intensity can preserve endurance and muscle strength.

Cessation in training, whether planned or unplanned, is a common occurrence in the life of all individuals, especially athletes, as it relates to the management of injuries or time spent off following a competition. Joe Cassaro explores ‘how much is enough?’ to maintain endurance and strength performance outcomes. 

Boxing – Boxer Kiaran MacDonald during a training session with strength and conditioning coach Andy Coulson at Unit 29 Fitness. REUTERS/Lee Smith

The cessation of training for four weeks is enough to see significant losses in endurance and strength measures(1,2). The effect of resistance training cessation is more prominent in individuals greater than 65 years of age(2). Additionally, when looking at maximal force and power production, the impact of resistance training cessation is more significant for untrained individuals compared to that of recreational athletes(2).

Short-term (days to weeks) training cessation, i.e., tapering, may allow athletes to recover from intense training periods and reduce the risk of overuse injuries. However, athletes will experience significant losses in endurance and strength performance when cessation extends beyond four weeks. The residual training effect (RTE) is the duration athletes retain the physical adaptations associated with training after cessation and occurs at varying rates (see table 1)(3).

Table 1: The duration of the residual training effect (RTE) for different motor abilities(3).

Motor abilityRTE, days
Aerobic capacity30 ± 5
Maximal strength30 ± 5
Anaerobic glycolytic endurance18 ± 4
Strength endurance15 ± 5
Maximal speed5 ± 3

 

Recovery from injury places the athlete and clinician at a crossroads. For example, the preservation of performance and recovery from injury may be the objectives when managing an acute or chronic injury. In such instances, athletes may need to allocate more time to recover from injury, and thus the maintenance rather than the development of performance may be the primary goal.

Factors that affect the magnitude and rate of decay(1).

1. Training history

2. Initial performance values

When describing the minimal dose needed for the maintenance of athletic performance, it is essential to define the variables clinicians may manipulate in exercise prescription (see table 2).

Table 2: Definitions of exercise prescription variables in strength and endurance training(1).

 Endurance and strength training
FrequencyHow often the client should train - prescribed as sessions per week
VolumeThe total amount of work required - prescribed as total distance, total time, or the number of sets and reps
IntensityHow hard to train - how much weight to lift or how fast to run

 

How much is enough?

  1. Endurance

Researchers at the Military Performance Division in the USA conclude that short-term endurance can be maintained for up to 15 weeks when exercise frequency is reduced to two sessions per week if the session intensity and volume remain unchanged. However, should the maintenance of athletic performance in highly trained individuals be the primary goal, clinicians and athletes should not reduce the weekly training frequency by more than 20%(1).

However, should clinicians manipulate the training volume, short-term endurance can be maintained for up to 15 weeks when exercise volume is reduced by 66%. These sessions may be as short as 13 minutes if the frequency and intensity of training is unchanged. In long-term endurance, i.e., exercise between one to three hours, athletes should only reduce the volume by 33%(1).

Although athletes may maintain endurance performance despite significant reductions in frequency or volume, reductions in intensity have radical implications for physical performance. Intensity is vital for the maintenance of endurance performance. Despite a high frequency (six sessions per week) and considerable volume (40 minutes per session), athletes struggle to maintain endurance adaptations(1).

  1. Strength

When examining the manipulation of frequency on the effects on 1-rep max (1RM) strength, a reduction from two or three training sessions per week to one is sufficient to maintain strength and functional performance if training volume and intensity were maintained(4). To partially maintain 1RM strength, athletes may reduce the frequency to one training session every two weeks(1,5).

Clinicians may select to manipulate the frequency in conjunction with volume in load-based injuries to reduce the tissue stressors. One set per exercise performed once per week can maintain strength in young and older athletes if the intensity is maintained. These results demonstrate that, as with endurance training, intensity is the foundation of strength development. Intensity should remain at a near-maximal effort to maintain strength(1).

  1. Muscle size

Hypertrophy and muscle bulk indicate strength and are essential outcomes in managing various sports injuries, e.g., anterior cruciate ligament injuries(6). For muscle size, the minimal frequency necessary to maintain adaptations may depend on the age of subjects. In younger athletes between the ages of 20 to 35, one strength training session per week is adequate to maintain muscle size. However, two sessions per week with a minimal volume of 2–3 sets per exercise is an effective dose for older athletes(1).

Conclusion

The cessation of training for periods lasting greater than two weeks is common across all trained and untrained populations for various reasons. Across this period, complete training cessation will likely lead to decreases in performance and the potential for increased injury risk. Minimal time spent training is needed to maintain performance gains for both strength and endurance. However, the minimal effective dosage to maintain strength and endurance is different from the optimal dose to improve performance.

Sports injuries are associated with time away from the training and sport; the maintenance of tissue capacity is paramount to ensure that athletes are ready and robust when returning to sport. Therefore, clinicians should prescribe adequate intensity in rehabilitation throughout the return to sport process.

References

  1. J of Str and Cond Res: 2021; 35 (5): 1449-1458.
  2. Scan J of Med & Sci in Sports. 2013; 23 (3): 140-149.
  3. J Sports Med Phys Fitness: 2008;48(1):65-75.
  4. Med Sci Sports Spring 1973;5(1):29-33
  5. J Strength Cond Res2011;25(10):2653-60.
  6. Int J Sports Phys Ther. 2019;14(1):159-172.
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