Most players hear "strength training" and think of big muscles and a bodybuilder's gym. That's not the goal for a tennis player. Strength training means making your muscles work against a resistance, then adding a little more week by week. The resistance can be weights, bands or your own body weight. Here's why it matters for tennis, what the research says about teenagers, and which common beliefs don't hold up.
What changes in your body
Your body adapts to what you ask of it. That change is built between sessions, with enough sleep and food. Strength training changes four things.
- Nervous system. In the first weeks, a big part of getting stronger comes from your brain and nerves. Your body learns to use more muscle fibres at once and to make your muscles work together better. In children, most of the gain comes this way.
- Muscle. Muscle fibres get stronger and a bit thicker. This starts in the first weeks, but it's slow.
- Tendon. Tendons connect muscle to bone. In studies on adults, heavy loading made them stiffer.
- Bone. Bone responds to load too. In children and teenagers, activities that load the bones helped build bone, but the effect was small. Calcium intake mattered too.
Why strength helps on court
Tennis is short quick steps, sudden stops, changes of direction and powerful shots. Strength sits behind all of them.
- First step and speed. Stronger legs push the ground harder. In a review of 15 studies, when squat strength went up, sprint times got better too. In young people, strength training improved sprint speed more than jump training did.
- Braking and changing direction. To stop fast, your muscles have to handle a lot of force while they brake. Stronger players tend to change direction faster. That link mostly comes from studies that compare players, like one in 12 elite basketball players. Treat it as a link, not proof.
- Reaction. Reacting to the ball doesn't seem to come from strength alone. In that same basketball study, reactive agility didn't line up with strength. Reaction needs its own practice.
- Serve and shots. A 2026 review of 20 tennis studies with 606 players found that resistance training raised serve speed. Not every study found faster shots, and accuracy didn't improve. One programme even made it worse. Strength doesn't replace technique.
- Late in a long match. I couldn't find a tennis study showing that strength training keeps your quality late in a match. In runners, it often made each step cost less energy, though not in every study. It makes sense that this could help in the second hour of a match, but nobody has tested it in tennis. You need aerobic fitness too.
Padel has the same stops and turns, but I couldn't find padel strength trials. For padel, this is sound reasoning and not a proven result.
A body that can handle the load
Every week of tennis means thousands of steps, stops, small jumps and serves. Your muscles, tendons and bones have to handle that load again and again. Strength training raises what they can handle, because you add load slowly and give them time to adapt.
One review pooled 25 trials with 26,610 people. Programmes built on strength training went with fewer sports injuries. Stretching-only programmes didn't show that. A second review, of six trials in people aged 12 to 40, pointed the same way.
This is a finding, not a promise. The results varied a lot between trials. I couldn't find a tennis or padel trial that tests it, and no programme can promise you won't get hurt.
Teenagers and strength training
A Canadian position paper says that with proper methods, strength training for children and teenagers is relatively safe. A 2014 international consensus, endorsed by sports medicine and paediatric groups, sets out how to do it well. The conditions: a well designed programme, slow progress, proper technique coaching and qualified supervision. The World Health Organization also recommends regular muscle-strengthening activity for every age group.
- Strength and muscular endurance improve well with the right training and slow progress.
- Balance and coordination can improve too.
- Bone responds to load in the growing years, and calcium matters.
- Young players who specialise early in one sport may build less general fitness. Strength work helps fill that gap.
Common beliefs, and what the research says
The research shows a different picture.
- "It makes you bulky and heavy." In a 9-month study of 24 college women tennis players, body weight didn't change in any group. The players on a multi-set periodised programme added a little muscle, lost some body fat and served faster.
- "It makes you slow." The opposite. In research, stronger legs went with faster short sprints, and in young people strength training beat jump training for sprint speed.
- "It makes you stiff." In a review of 11 trials, strength training and stretching improved range of motion about the same. The trials varied a lot.
- "It stunts your growth." In a review of 22 studies of children and early teens, supervised weight training didn't affect growth in height or weight.
- "It's only for professionals." The World Health Organization recommends muscle-strengthening for every age group. Expert reviews say a stronger young player is better prepared to learn complex movements and to handle training and matches.
- "Tennis and running are enough." Tennis builds tennis fitness. In my view it doesn't raise the load on all your tissues, step by step, the way planned strength work does. That's my reasoning, not a trial result.
Keep it going
Strength you stop training fades. In the youth studies reviewed, the gains were lost when training stopped. In a busy match week, my suggestion is a shorter session instead of none.
Based on Folland and Williams (2007), Behm et al. (2008), Seitz et al. (2014), Lauersen et al. (2014), Malina (2006), Kraemer et al. (2000) and Hu et al. (2026).