Perfect Your Training Intensity For Your Best Results Work smarter? Or harder? Balance is key to optimal performance and decreased injury risk.

Training harder and smarter.

Which are you…

The person who never stops training?  The one who tries to outwork the competition?

Or the person constantly looking for a way to hack the system?  (The one taking a break from Tim Ferriss’ 4 Hour Body to read this post?)

Which is better? 

Or, from a health perspective, which increases injury risk?   Overtraining or undertraining?

Answer – both.  Working way too hard is just as bad as not working hard enough.  

*Note-  we’re talking about non-contact, overuse injuries here.  These are preventable.  Contact injuries are a different story.  We don’t have as much control over what happens when two players collide on the soccer field or basketball court. 

Balance training harder and smarter.

Finding the balance…

The best sports performance programs aim for a “sweet spot” where training is intense enough to make athletes better, faster, stronger… but not so crazy that it causes injury (which would clearly not help those goals). 

Regardless of the sport, we should look at two factors when building training programs:

  1. How intense the training is (also known as “load”)
  2. How fast to “ramp up” that intensity

Let’s define “training” a bit further…

Acute training = amount of workouts in the past week  

Chronic training = average amount of workouts over the past 4 weeks 

Think of acute training like “fatigue” – how tired are you from your training sessions or workouts over the past week? 

Chronic training is basically looking back on the past few weeks and reflecting on “how fit you are” overall from those workouts.

Objectively comparing how you feel now to how you have felt over the past 3-6 weeks gives interesting data on how ready you are for competition.

Let’s use running as an example.  If an athlete has taken it easy the week before a race but has a good base of mileage in previous weeks, they are ready to run.   Their acute training would be classified as low (not tired, well rested) but their average chronic training is high (they built a base of endurance over the past few weeks).  

I coach a distance running program through my local running store.   We prepare runners for half and full marathons over the course of a 15 week training cycle.  The training program hits peak mileage 11 weeks before race day.  The last couple weeks leading up to the race are “taper” weeks designed to decrease the acute training load on our runners.  The goal is to feel fresh-legged at the starting line but still have the capacity to run either 13.1 or 26.2 miles.  

Taper weeks are always a source of stress for our runners who worry they’ve not run high mileage during that time, but as you can see, there is scientific data backing our recommendations to taper.

Now let’s define “load”…

Load is basically a measure of how intense a training session is or how stressful your last workout was on your body.  Three things make up an athlete’s load:

  1. External training load:  “work” or “volume” (total distance run, amount of weight lifted, number of sprints, jumps to rebound a basketball, collisions in football, etc…)
  2. Internal training load:  the body’s response to the training (rating of perceived exertion, heart rate, blood lactate, oxygen consumption)
  3. Individual characteristics of the athlete: age, experience, injury history, physical capacity

Training outcome =  external load + internal load + individual characteristics of the athlete 

All these factors are important in determining the effect of a given workout.  The same external load could have a different internal effects based on the individual-  think about how a 21-year-old collegiate runner would do on a 4 mile run versus a 40-year-old athlete that started running only a few weeks earlier.  

The workout is too intense for the 40-year-old but too easy for the 21 year old.  The 40 year old would be at risk for injury, where the 21 year old wouldn’t gain any training effect.

The same external load could have a different effect on the same athlete as well.  Someone could do a workout feeling tired, stressed, or fatigued from a tough week of training.  Or they could repeat that workout (same external load) after a great night of sleep or easy week of training.   

Never underestimate the effect of “life” factors on a workout like emotional disturbances, illness, stress, or recent training history.  Respect them and modify workouts accordingly. 

Tracking external load:

For endurance athletes like runners, swimmers, and cyclists, this is easy to monitor.  GPS watches can log distance and speed covered.  Personally, I’ve been using this Garmin model for over a year with great results.    

Some elite/pro teams are using GPS-based sensors to detect the number of jumps in volleyball, collisions in rugby or football, strokes in swimming, number of sprints per game in soccer.  These teams can scale up or scale down training between games based on how much load a particular athlete had in competition.

Since GPS watches are not really useful with weight training, calculate the load like this:

External load = (number of repetitions x kilograms of weight lifted)

Tracking internal load:

Rating of perceived exertion is one of the easiest ways to track internal training load.  Rate the intensity of the session on a scale of 1-10.  Multiply that rating by the length of the training session (in minutes).

Internal load = RPE (scale 1-10) x minutes of training

This score could also be called “exertional minutes.”  Researchers are still collecting data on different measures of “high” or “low” exertion for various sports.   For now we consider a score of 300-500 in football players as a low intensity training session.  700-1000 is higher.  

Heart rate or VO2max multiplied by training minutes would also be another way to track internal load.  Or blood lactate concentration to get really technical (and invasive).  

There are other scales used for elite athletes like the Recovery-Stress Questionnaire that track mood, stress level, energy, sleep and diet, soreness, etc.   The sum of these questions indicates the athlete’s well-being, and coaches or strength and conditioning experts can adjust workouts accordingly. 

Individual characteristics:

Studies on rugby and Australian Football players show that age influences how athletes respond to conditioning programs.   Research also shows older athletes are at higher risk for overuse injuries.

But…is the injury risk from workouts that are too intense?  Or because older athletes tend to have a greater incidence of prior injuries?  History of past injury is a major risk factor for new injury.  

Regardless, a training program should be individualized to the athlete’s age, experience, injury history, and overall physical capacity.  

General training concepts stay the same, regardless of the sport

Calculating your own training load.

You can use external/internal load and acute/chronic training to decide if you are in the optimal training zone for your goals (or find out are at risk for injury before it’s too late). 

Let’s take the running example I used earlier- 

“Peak weeks” for a half marathoner (weeks of 8-11 of a 15 week program)

 Week 8: 21 miles

Week 9: 23 miles

Week 10: 25 miles

Week 11: 30 miles

Acute load (mileage week 11) = 30 miles

Chronic load (average mileage 4 weeks prior) =  24.75 miles

Now, take the acute load (30) and divide by the chronic load (24.75) to get a ratio:

Acute load ÷ chronic load = acute:chronic load ratio

30/24.75 = 1.21

“Taper weeks” for the same race (weeks 12-14):

Week 12: 24 miles

Week 13: 23 miles

Week 14: 18 miles

(Week 15: race week) 

Acute load (mileage at week 14) = 18 miles

Chronic load (average mileage of the 3 weeks prior) =  21.67 

Again, calculate the ratio:

Acute load ÷ chronic load = acute:chronic load ratio

18/21.67 = 0.83

Acute to chronic training ratio

Research shows the “sweet spot” or optimal zone for training is a ratio between. 0.8 and 1.3.  

So the runner is in the optimal training zone during the “peak weeks” above, and has built enough of a mileage base to stay in that zone through the taper and entering race week. 

The same research has also shown us that a ratio above 1.5 is the “danger zone” for training.  Increased injury risk is higher in the weeks after training at this kind of load.  

How many of us have been in this situation?  We feel great on a particular training week so we continue to ramp up the intensity.  As the workouts get harder, initially we feel invincible… then the wheels fall off.  An injury happens “out of nowhere,” leaving us wondering what went wrong. (if I had a dime for every time I’ve heard, “but I felt so GOOD, Carol!  I don’t know what happened?!?”).  

Don’t worry, I’ve made the same mistake too.  Many times.  Unfortunately this is an easy trap to fall into.   Monitoring your acute to chronic load ratio can reduce risk of this happening.

But I don’t run.  I hate running.  

I (lift weights, do CrossFit, play soccer, insert sport here…).  How do I track my training?

Same concepts apply!

  1. Calculate your acute training load over the past week

Number of repetitions x kilograms of weight lifted

or…number of sprints, minutes of soccer practice, etc…

  1. Find the chronic training load (average over the past 4 weeks)
  2. Divide the acute load over the chronic load and compare to the figure above
  1. Remember to take into account internal training factors and individual characteristics


  1. Intensity matters  both overtraining AND undertraining put athletes at risk for injury.  A training program must get the athlete ready for the demands of their sport, but the coach and athlete need to understand it may take a several weeks to get to this point. (see point #2)
  2. Sudden increases in training intensity puts athletes at risk for injury.  Monitor acute training (how fatigued you are over the course of a week) and compare it to chronic training (how “fit” you have been over the past few weeks) 
  3. Monitor the body’s response to training – the internal training load.  Use rate of perceived exertion x number of minutes spent training.
  4. Think about other factors  age, stress, sleep, etc.  These are important!


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