How hard should a set feel? Reps in reserve, explained

Most players walk into the gym with one instruction for themselves: work hard. It is not a bad instinct, and it is a poor plan, because it cannot be repeated. Some days it means eight reps that felt fine, some days it means eight reps that felt like a match tiebreak, and nothing can be compared to anything.

Reps in reserve fixes that with a single habit: after the last set, you ask yourself how many good reps were still left in the tank.

What the numbers mean

• RIR 4 or more. The set was comfortable. Useful in a first week or on a deload, not a training stimulus for long.
• RIR 3. Three good reps left. Moderately hard, technique stays clean, the next court session is safe.
• RIR 2. Two reps left. The working zone for most strength training in tennis players.
• RIR 1. One rep left, and it would have been a grind while the bar slowed down.
• RIR 0. Failure. The rep was not completed, or it was completed with nothing left.

The plan usually asks for RIR 2 to 3 on the main lifts. That is not a compromise. It is close enough to the limit to build strength, far enough away to protect the movement and the next two days of training.

Why not simply train to failure

Failure trains the skill of failing. The reps get slow, the lower back takes over the last part of a squat, the shoulder shifts forward on a press, and the athlete learns a shape they do not want on court.

It also costs more than it pays. A set taken to failure adds fatigue out of proportion to the extra stimulus, and tennis already loads the same legs and shoulders on court. A player who leaves two reps in the tank three times a week for eight weeks will be stronger than a player who empties the tank once and then needs two easy days to recover from it.

How to judge the last rep honestly

You cannot count reps in reserve perfectly, so judge it by the movement instead of the feeling:

1. Did the bar slow down noticeably on the last rep?
2. Did the shape of the movement change: the knees drifting in, the chest dropping, the tempo becoming a bounce?
3. Could you have repeated that rep with the same technique, right now?

One clear yes to the first two, or two good reps available from the third, and you are in the right zone. If you could have done six more, you were further from the target than you thought, and the next set is the place to fix it.

What it changes the next session

The number is only useful because it points at a decision. Two of them:

• Load. Finished every set at the prescribed RIR and the last one felt easier than last week? Add a small amount of weight next time, around two to five percent. Not a jump, an increment.
• Back off. Needed the reps but the technique went, or slept badly, or played a two-hour match yesterday? Keep the load and take one set off. Volume is easier to recover than a sloppy set.

This is what progressive training actually looks like: the same movements, inched forward, judged against the last time rather than against how hard today feels.

Where reps in reserve does not apply

Speed, jumps, throws and fast change of direction are not trained near failure. The rep ends when it gets slow, and every rep is meant to be the best one. The same goes for mobility and warm-ups, where the point is the position, not the effort.

Strength work is where the number belongs, and it is the reason the weight you enter in your session only needs to match the effort you were asked to produce.

The short version

Train most sets at two or three reps in reserve. Add a little weight when the last set matches the target and feels easier than last week. Stay away from failure unless a session specifically asks for it. One number, recorded every set, and eight weeks of training becomes a comparison instead of a memory.