High-intensity training methods that avoid injuries. Important points to keep in mind to improve athletic performance.

High-intensity training is essential to improving athletic performance.
However, on the other hand, there are probably many athletes and coaches who have had the experience of "I suddenly started to feel pain as soon as I increased the intensity" or "I tried too hard and ended up getting injured."

The important thing is that it's not the intensity itself that's bad, but rather the way the intensity is increased and the physical condition of the body that can withstand it that is the problem .
In this column, we will introduce the key points for performing high-intensity training while avoiding injury.
We will cover two aspects: 1) appropriate load setting and form accuracy, and 2) fatigue management.

* Appropriate load setting and accuracy of form

When it comes to training load, the heavier the load, the more effective it is; the appropriate number of repetitions and weight will vary depending on your goal .
Resistance training (muscle training) is generally organized as follows:

  • Maximum strength improvement: 6 reps or less
  • Power Increase
  • Single shot power: 1-2 times
  • Multiple shot power: 3 to 5 times
  • ● Muscle hypertrophy: 6-12 times
  • ● Muscle endurance: 12 or more repetitions

Power here is "force x speed."
Single-shot power is the ability to exert great force in an instant, such as in the shot put or high jump.
On the other hand, frequent power is the ability to repeatedly exert high power, such as in continuous jumps or repetitive movements during play in sports like volleyball or basketball.

However, more important than the load is the accuracy of your form .
For example, if you continue to perform heavy squats with your knees turning inward and your core collapsing, damage to your joints and ligaments will accumulate before your muscle strength improves.
Therefore, before increasing the intensity, checking whether the same form can be consistently reproduced using video or from a third-party perspective will lay the foundation for safely increasing the load.

A useful metric that ensures accuracy of form is the Acute-Chronic Load Ratio (ACWR) .
ACWR is calculated by dividing the load over the most recent week by the average load over the past four weeks, and quantifies the "suddenness" of the load increase.
Studies have shown that a ratio between 0.8 and 1.3 reduces the risk of injury.

How to calculate the Acute-Chronic Load Ratio (ACWR)

Internal stress : Subjective intensity 0 (very weak) to 10 (very difficult)
example:
Weekly subjective average intensity 7 x average training time 100 minutes
Average subjective intensity over 4 weeks including week 1 x average training time 110 minutes
Weekly average 700 ÷ 4-week average 660 = 1.06

External load :
Example: Running intensity (speed/distance/time), number of jumps, lifted weight/number of repetitions
Average weekly distance: 5km
Average distance traveled over 4 weeks: 3km
5 ÷ 3 = 1.6

As shown above, the acute to chronic load ratio (ACWR) of the training was 1.04 for internal load and 1.6 for external load. Since the external load is excessive, it can be said that there is an increased risk of injury.

Fatigue management

Fatigue has more than one cause.

  • Muscle damage and inflammation
  • Accumulation of fatigue substances
  • Lack of energy
  • lack of sleep
  • Brain fatigue (stress caused by information overload)

As fatigue accumulates, form becomes more likely to break down, leading to increased localized stress.
It's not enough to train every day; it's also important to take one day off per week to allow your muscles and body to recover from the damage caused by training .

Summary

The important thing about training is not whether you can do it or not, but whether it is being built up safely .
Gradually increasing the load while constantly checking the accuracy of your form and your sense of fatigue is the quickest route to preventing injury and improving your competitive ability.

Author
Minori Nakayama, Physical Therapist at Ikejiri-Ohashi Sera Clinic
Supervision
Dr. Yasushi Sera, Ikejiri-Ohashi Sera Clinic
Ikejiri-Ohashi Sera Clinic