For the longest time, there was a thought process which promoted we shouldn't conduct strength training for athletes in season. It held a belief which claimed in-season strength training would lead to overuse injuries or provide athletes too little time to recover before games or practice. Thankfully, we know better at this point, and have realized strength training throughout the season is not only highly beneficial, but imperative in maintaining strength and power outputs for the duration of the season. With this said, there still is some conflating thoughts about what in-season training should look.
There are some "camps" out there promoting high-rep, low-weight training sessions as a way of training during season, and others who are promoting low-rep, high-weight training sessions during season. To claim either of these as being wrong would be too dismissive of the benefits both of these approaches for training in-season. In order to understand which approach to use, we need to understand the benefits of each and how to apply it within the frame of a season efficiently.
High-Rep, Low Weight
These could be considered restorative sessions. A fair amount of isolation work, performed in a relatively short time frame, with the primary goal of increasing blood flow to muscle tissue. This allows nutrient supply to the tissue to be high and allow for healing and restoration to happen. This is a good thing for in-season, but we have to keep in mind any of the side effects as well.
Volume is the hardest thing to recover from. The more reps you do, the more time under tension you spend (TUT). The more TUT you have, the greater damage the muscle accumulates. So while high-rep, low-weight strength training can be beneficial to increasing long-term muscle recovery, it poses a risk for increased soreness on game-day and also does not expose the body to high forces like the ones experienced in games or matches. Understanding this is key when learning to apply this style of training during season.
Low-Rep, High-Weight
These could be considered high intensity sessions. The Rating of Perceived Exertion (RPE) per rep and set is higher, while the overall volume is very low. This is great for creating high-force outputs, and allows the body to maintain (or even increase) it's ability to produce high forces during a game. Progressive overload is more easily attained through increased loading than it is through volume and density, so the promoters of this method are quick to point out how this helps when leveraging full levels of force output to make gains while in-season.
The downside to these sessions are how they require higher neural drive and how they create a demand on the nervous system to maintain the overall force output. For individuals who have had time to "unwind" after a game, their overall level of fatigue and neural dampening may be rather high. This makes heavy lifting within close proximity to post-game a little more challenging (especially in skill-dominant sports or for skill-dominant positions). Again, knowing this can help us utilize this method more accurately in-season.
When looking these two commonly promoted approaches, perhaps a combination of both work best?
If you have multiple games within a week, or even a singular game to plan training around, you can utilize both of these approaches fairly well. As long as you have a timeline and a schedule for those games or matches, implementing both approaches can be highly beneficial to an in-season athlete. The key is knowing when to implement each in relation to a game.
To showcase this, let's assume an athlete is a volleyball player with games on Tuesday and Friday. The team lift schedule has them training on Monday, Wednesday, and Friday (if you're in the private setting for training, this may still be the case for an individual based on availability). You're going to want to ensure you have the least amount of muscle damage prior to game day, and are still able to produce force.
In this instance, you'd want to hit lower volume, higher intensity lifts on Monday and Friday, with an emphasis on lift speed. This may look like 3 sets of 1 rep at 85% of a 1RM, or if you're using RPE it would be closer to an RPE8. These lifts shouldn't take long, and should have a relatively low impact on the nervous system. Does this mean we are maxing out? No. But it does mean the low repetition efforts should be high effort, leaving enough gas in the tank for a Tuesday game.
Sticking with this progression, we'd hit our high-rep, low-weight session on Wednesday. This allows for blood flow to be supplied to a muscle which has likely accrued a little bit extra damage from the previous night's game, and starts the recovery process. This may look like doing some isolation work for 2-3 sets of 10-15 reps, and utilizing machines if available. This allows us to let the nervous system recover from repeated high force or power outputs from a game, while still getting some work in to deeper muscle tissues. This added time under tension is also key for avoiding chronic injuries such as tendinitis and sprains/strains which inhibit play.
Now, is this a fool proof system? No. Every approach will have some nuance and limits. The big key here is the concept and the placement of style of workouts. The closer we are to pre-game, the higher the relative intensity and the lower the volume we want sessions to be. The farther away from a game (or the first workout after one), the higher volume and lower relative intensity we want sessions to be. Now, for consistent or back to back games, we want to sway more towards the low-rep, high-weight side of the spectrum. Especially for efficiency sake and keeping force outputs high, being able to continue to improve that ability across a season.