How Many Jumps Does It Take to Condition Your Tendons?

For a sedentary adult, about 100 jumps per workout, three times a week for four weeks, may be enough to measurably change Achilles tendon mechanical properties. That is the useful finding from a small randomized trial—not proof that 1,200 jumps is the universal minimum dose, and not proof that those changes prevent injury. It is an early estimate of where tendon-related measures began to move.

The same study found a different threshold for strength. Participants who completed about twice as many jumps improved two isokinetic strength measures, while the lower-volume group did not. Tendons and muscle may respond on different timelines, but this result comes from 44 people, four weeks of training, and measurements that do not tell us whether anyone became safer, faster, or more capable in daily life.

The 1,200-jump result

In a 2024 randomized controlled trial by Torres-Banduc et al., 44 sedentary adults entered one of three groups: a control group (n=16), a reduced-volume plyometric group (n=16), or a full-volume plyometric group (n=12). Both training groups completed supervised plyometric training three times weekly for four weeks, with volume increased gradually.

The reduced-volume group accumulated approximately 1,207 jumps across 12 sessions—about 101 jumps per session. The full-volume group completed approximately 2,414 jumps, or about 201 per session. After four weeks, the reduced-volume group had statistically significant changes in three myotonometry-derived Achilles tendon measures: stiffness (p=0.04), decrement (p=0.01), and relaxation (p=0.02).

These measures describe aspects of how a tendon responds to a mechanical tap. Stiffness relates to resistance to deformation; decrement and relaxation describe damping and recovery behavior. They are plausible indicators of tendon adaptation, but they are surrogate measures. The trial did not report fewer injuries, less pain, better running economy, or a lower risk of an Achilles problem. A changed instrument reading is not a clinical outcome wearing a trench coat.

The higher-volume group did not show additional gains over the reduced-volume group on those tendon measures. That makes the lower-dose result interesting: more jumps did not produce a bigger measured Achilles response within this short study. It does not establish that 1,207 jumps is the minimum effective volume. The researchers did not test lower doses such as 25 or 50 jumps per session, so the true threshold could be lower.

Strength appeared to need more work

The full-volume group did show significant improvements in selected isokinetic outcomes. During the standing-up phase at 15 cm/s, its value reached 10.0 ± 3.3 N/kg and differed from both the control and reduced-volume groups (p=0.01). It also improved during the sitting-down phase at 5 cm/s (p=0.002). The reduced-volume group did not reach a measurable strength gain during the four-week intervention.

This pattern supports a modest practical idea: early tendon-related changes may appear before measurable strength changes when an inactive person begins jumping. It does not prove that tendon collagen needs less loading than muscle. The trial did not measure collagen remodeling, muscle hypertrophy, neural adaptation, or any mechanism that could explain the split.

It also did not use the usual angular-velocity format common in isokinetic knee testing. The reported standing-up and sitting-down phases at linear velocities of 5 and 15 cm/s make it hard to translate the results into familiar strength benchmarks. Statistical significance tells us the group differences were unlikely to fit the study's null model; it does not establish how large or meaningful the functional change was.

Four weeks is a very short runway for performance

A larger 2023 systematic review and meta-analysis by Ramirez-Campillo et al. puts the short protocol in perspective. Across 61 studies and 2,576 healthy participants, with moderate-certainty GRADE evidence, plyometric jump training improved reactive strength index. Programs lasting more than seven weeks, delivering more than 14 sessions, and using three weekly sessions produced better reactive-strength outcomes than shorter, lower-session, or less frequent programs.

The Torres-Banduc program matched the favorable frequency—three sessions per week—but lasted only four weeks and included 12 sessions. That matters for interpretation. The absence of a strength gain in the reduced-volume group may reflect too little total jumping, but it may also reflect too little time. Extending the lower-volume program beyond four weeks could produce strength changes that this design missed. The trial therefore identifies two tested doses over one short period, not a clean biological dividing line between tendon and muscle.

The meta-analysis measured reactive strength index, not Achilles myotonometry and not the unusual isokinetic outcomes used in the trial. It cannot confirm or refute the 1,207-jump tendon finding. It does, however, make one conclusion hard to defend: four weeks is not enough evidence to prescribe a low-volume program as an optimized route to better plyometric performance.

Can we trust the tendon measurements?

The trial used myotonometry, a handheld method for estimating mechanical properties from tissue response. A 2024 study by Szajkowski et al. evaluated the reliability and accuracy of Achilles tendon myotonometry in CrossFit athletes. That is useful proof that the tool can be studied carefully in a trained population.

It does not settle reliability in sedentary adults. Tendon structure and tissue behavior can differ with training history, and the available study did not establish that the same reliability estimates apply to people starting from inactivity. Nor is there universal agreement that myotonometry captures the same construct as ultrasound-based assessments of tendon stiffness. The Achilles results deserve attention, but their exact numerical threshold needs replication with multiple measurement methods.

Why other tendon studies do not settle the question

Tendon adaptation depends on the tendon, athlete, loading plan, and time frame. In young female soccer players, a 2023 randomized trial by Lee et al. examined patellar tendon changes during 10 weeks of mixed bodyweight strength, plyometric, and pitch-based training, alongside collagen hydrolysate or placebo. That population and intervention differ sharply from sedentary adults performing a four-week Achilles-focused jump program.

Likewise, a 2025 study in professional female soccer athletes reported patellar tendon adaptations after high-intensity resistance training with collagen supplementation. Trained professionals, the patellar tendon, added resistance work, supplementation, and a longer intervention cannot tell us whether 1,200 jumps conditions a sedentary person's Achilles tendon. They do show why a single jump count should not become fitness folklore.

Research on landing-focused neuromuscular programs also should not be treated as a safety certificate for this protocol. A 2025 review of youth female athletes assessed jump-landing biomechanics and ACL-injury implications, not Achilles outcomes in sedentary adults. The Torres-Banduc trial itself reported no injury-incidence data, leaving the safety profile of its entry-level volume unknown.

What a sedentary beginner can reasonably take from this

About 100 jumps per session, three times weekly, is a research-tested starting volume at which a small trial detected changes in Achilles tendon stiffness, decrement, and relaxation after four weeks. It is reasonable to treat that as an exploratory ceiling for a structured beginner progression, not as a requirement and not as a medical prescription.

Start with a progressive warm-up and a jump variation you can land quietly and control. Spread repetitions across sets instead of chasing fatigue. If you have current Achilles, knee, hip, or foot pain; osteoporosis; poor balance; a recent injury; or a condition that affects exercise safety, get individualized advice before adding impact work.

Expect strength and jump performance to take longer than four weeks. The stronger evidence for reactive strength favors three weekly sessions continued beyond seven weeks and more than 14 sessions. For now, the honest verdict is narrow: a four-week program of roughly 1,200 jumps may alter Achilles mechanical readings in sedentary adults, while roughly double that volume produced selected strength gains in one small trial. Replication, injury data, and lower-dose comparisons still have work to do.

Measured tendon properties changed at about 1,200 jumps in one trial. The study did not establish the minimum safe dose, the minimum effective dose for injury prevention, or a universal training prescription.