The phrase “over-trained” gets thrown round a lot in our industry. It’s true that the cumulative effects of training, competitions, and not enough rest can start to wear down an athlete to a detrimental point. So we should not consider ourselves relegated to the monitoring of exercise prescription and volume management in the weight room, as the most profound effect we can have is regulating and managing what is happening in the sport itself. Yet, without an accurate way to quantify all that stress, how do you know for certain that an athlete is over-trained? Training Stress Balance is a good start.
Training Stress Balance (TSB) compares the amount of training you have done over the last seven days to your average work load. The last seven days is quantified and called Acute Training Load (ATL) and then compared with the average amount you have done over the last 21-42 days, called your Chronic Training Load (CTL). The ATL and CTL are often informally labeled “fatigue” and “fitness” as well.
A positive TSB score means that your training over the last week is less than your average, therefore you are well rested. A negative TSB means you have done more over the last week than your training average and you are starting the process of over-reaching. A negative TSB is indicative of a high training load, i.e. high ATL relative to CTL, would occur in a high load training week. Alternatively, a period of taper leading up to an event should correspond with an increasing TSB where ATL is reduced relative to the current CTL.
How is TSB measured? Any stress variable that can be qualified (pitches for baseball, distance from GPS for rugby/soccer, sprinting distance for American football) can be measured to create the 3-6 week average, and then used to compare the most recent week of stress. In this example, the researchers in England studied fast cricket bowlers. The study looked at players’ ATL and CTL over a 6 year period for both internal load and external load. Internal load was calculated off Rating of Perceived Exertion (RPE), while external load was the total number of balls bowled in practice and competition. The TSB was calculated differently by dividing ATL by CTL and displaying the balance by a percentage.
The results indicate that injury risk increases as the acute workload outweighs the chronic workload. Furthermore, the greater the increase in acute workload relative to chronic workload, the larger the increase in injury risk in the following week. This was highlighted by the threefold and fourfold rises in injury risk for external and internal workloads, respectively, when the TSB exceeded 200%, compared with 50-99%.
We are applying the same strategy to the professional and collegiate baseball, collecting a 3-week rolling average of the pitchers’ pitch counts (chronic workload or CTL), so that the current week can be compared to hard data (not just anecdotal observations). They key to having a effective TSB program is consistent data management, as 3+ consecutive weeks of accurate data input is required for the CTL.
Since implementing a TSB program, we have found positive relationships to physical performance in baseball pitchers in acute performance (increased fastball speed-MPH). We are currently examining relationships of TSB to injuries to the upper body that would further strengthen the significant prediction of elbow injuries with certain movement signatures.