3.11 Hopping, Bounding, and Horizontal Plyometrics

The short version

Most jump training points straight up. Hopping and bounding are the branch that points forwards. A depth jump asks you to redirect force down and then up. A bound asks you to redirect it backwards and forwards while balancing on one leg at a time. That is a much closer match to what sport actually demands, because sprinting, cutting and nearly every field-sport action are horizontal problems, not vertical ones.

This article covers what these drills really train, how to build them up across five stages, how to work out what any given drill is going to cost you, and how to set the volume so the adaptation lands in your tendons and your movement pattern rather than in your shins.

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Bounding is a late-stage skill introduced far too early

You have probably seen this go wrong. A coach marks out thirty metres, says "big bounds, hang in the air", and off everyone goes. Two sessions later somebody has sore shins and the drill quietly vanishes from the programme. The drill was not the problem. Bounding is a stage four skill and it had been dropped in at stage one.

Look at what a bound is actually asking for. It is a single-leg jump from one foot to the other, travelling forwards, with a real moment of flight in between. That one sentence hides three separate demands: you have to survive landing on one leg at speed, you have to reverse that landing fast enough that the springy energy is still there to use, and you have to send the force out behind you rather than straight down underneath you. Every one of those can be trained, and every one has its own build-up drills.

Hop, bound and jump are not the same word. A hop is one leg to the same leg. A bound is one leg to the other leg. A jump is two feet involved. Sorting this out early is not fussiness — it changes what you are asking for. Repeated single-leg hops load the same limb over and over. Alternate bounds give each leg a rest between contacts. Same-looking session, completely different bill at the end of it.

Two things tell you what a drill costs. How long the foot stays on the ground, and how many legs are sharing the job. Get those two straight and you can slot any drill you have ever seen into the right place, and you can predict roughly how much of it somebody can handle. Everything else is detail.

Volume and intensity pull in opposite directions. Two hundred small, quick contacts is a legitimate session. Thirty maximal ones is also a legitimate session. What they are not is interchangeable, and swapping one for the other because it felt easier that day is how people end up injured. Pick a number for one and the other one is decided for you.

Measuring distance per bound only means something if you hold everything else still. Same number of bounds, same run-in, same surface. Change the approach and the number changes for reasons that have nothing to do with how you are progressing. A metre of extra distance from a longer run-up is not an improvement, it is arithmetic.

Skipping the horizontal stuff leaves a hole. Vertical jump training has dominated plyometrics for decades, largely because it is easy to measure. But a big vertical jump does not tell you much about how well someone pushes themselves forward, and forward is where the game happens. If your entire jump programme goes up and down, you have trained one axis and left the other alone.

Here is the entry test. Before anyone bounds for distance, they should be able to do twenty pogo hops in a row with a stiff ankle and a steady rhythm. If the ankle collapses or the rhythm falls apart at hop twelve, bounding is not a technique conversation yet — it is a tissue conversation, and the answer is more of the boring work.

The rest of the article goes into the detail: the five-stage progression, drill classification tables, contact-time and limb-demand guidelines, volume prescriptions, and testing protocols. Those sections are more technical, so read them when you want the mechanism rather than the map.

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The horizontal plyometric progression ladderFive stacked stages running from ankle stiffness drills at the base to maximal single-leg bounding at the top, each stage feeding the one above it.The horizontal plyometric progression ladderStage 1 — Ankle stiffness and rhythmPogo hops, line hops, low ankling and A-skips. Contact times are short but amplitude is tiny. The aim is a rigid foot-anklespring and an even rhythm, not distance.Stage 2 — Double-leg horizontal workStanding broad jump, repeat broad jumps, double-leg forward hops over low hurdles. Both limbs share the load while the athletelearns to project the body forward instead of upward.Stage 3 — Alternate-leg boundingSkipping for distance, then true alternate bounds. Ground contact lengthens slightly, hip extension range increases, and thearms begin to drive the rhythm.Stage 4 — Single-leg hoppingRepeated hops on one limb for distance, or over a fixed distance for time. This is the first point at which one limb absorbs andre-expresses the entire body mass with no partner limb to share it.Stage 5 — Combination and maximal boundingHop-hop-step, step-step-jump, single-leg speed bounds and depth drop to bound. Contacts are near-maximal in intensity and volumemust be kept deliberately low.

Figure 1. Horizontal plyometrics are built from the ground up. Each stage establishes a tissue quality and a motor pattern that the next stage depends on; skipping a stage is the most common reason bounding produces shin and calf complaints rather than speed.

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Hop, bound, and jump are not synonyms

The terminology is worth fixing early because programmes fall apart when it is loose. A jump takes off from two feet and lands on two feet. A hop takes off from one foot and lands on the same foot. A bound takes off from one foot and lands on the other. The triple jump is named for exactly this sequence: A hop, a step, and a jump.

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This is not pedantry. A single-leg repeat hop asks one limb to absorb and re-express body mass on every contact, which is roughly twice the per-limb exposure of an alternate bound over the same number of contacts. If your programme says "thirty single-leg contacts" and the athlete performs thirty hops on the right leg instead of thirty alternating bounds, they have done double the intended work on that limb.

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• Ground contact time The duration the foot is in contact with the ground during a single bound or hop. Short contacts bias the elastic and reflexive contribution; long contacts bias concentric strength.
• Amplitude How far the athlete travels per contact. High-amplitude bounding with long flight is a different stimulus from low-amplitude bounding with fast turnover, even at the same total distance.
• Reactive strength index Jump height or distance divided by ground contact time. It is the standard way of expressing whether an athlete is getting a good return for the time they spend on the ground.
• Stiffness The resistance of the leg spring to collapse under load. Too little and the athlete sinks; too much and they cannot absorb anything. It is joint and task specific rather than a single global quality.

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Why horizontal work is not optional

Vertical jump training has dominated plyometric programming for decades, largely because vertical jump is easy to measure. But the ground reaction force in a sprint is not oriented vertically for most of the acceleration phase, and the ability to produce force vertically does not automatically translate into the ability to direct it backwards (Edouard & Samozino, 2011).

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Figure 2 shows the shape of this relationship. In the first few steps out of a block or a standing start, a large share of the athlete’s force output is directed horizontally. By thirty metres, the athlete is spending far more of their effort simply keeping themselves off the ground, and the horizontal share has fallen substantially (Rabita, 2015). An athlete who only ever trains vertically has prepared for the second half of that curve and left the first half untouched.

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Force orientation shifts as sprint speed risesLine chart with distance on the horizontal axis and share of total force output on the vertical axis. The horizontal component starts high and falls; the vertical component starts low and rises.Force orientation shifts as sprint speed risesHorizontal force componentVertical force component0 m10 m20 m30 m40 m0%25%50%75%100%Distance from a standing startShare of total force outputBroad jumps and repeat broad jumpsBounding and single-leg hoppingSpeed bounds and sprint-float work

Figure 2. Early acceleration is largely a horizontal force problem and top speed is largely a vertical force problem. Bounding and hopping sit deliberately in the middle of this curve, which is part of why they tend to transfer to the ten to thirty metre window more readily than to the first two steps.

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This is why the broad jump correlates more closely with short-distance sprint performance than the vertical jump does in most published datasets (Lockie, 2014; Maulder & Cronin, 2005), and why horizontal plyometrics belong in any programme aimed at acceleration, change of direction, or field-sport performance.

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None of this means vertical work should be removed. Top-speed sprinting is a vertical force problem, and jumping sports obviously need vertical qualities. The argument is for including horizontal work, not for replacing one bias with the opposite bias.

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The mechanics and physiology in detail

What the tendon is actually doing

During a bound, the Achilles tendon and the plantar fascia behave like a spring that is loaded on landing and released at push-off (Cavagna, 1977). The muscle fibres of the triceps surae, meanwhile, do something closer to isometric work: They contract to hold a length while the tendon lengthens and shortens around them (Roberts & Azizi, 2011). This decoupling between muscle and tendon behaviour is central to why elastic drills feel different from grinding ones.

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The practical consequence is that the training target of a short-contact bound is not muscular force in the conventional sense. It is the ability of the muscle to stiffen fast enough that the tendon can do its job. If the muscle yields, the tendon lengthens too far, the timing is lost, and the energy that should have been returned is dissipated as heat. This is what a coach sees as "sinking" or "sitting" in the contact.

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• Landing: Tendon lengthens, muscle fibres hold near-isometric, elastic energy is stored.
• Amortisation: The reversal window, during which the stored energy is either returned or lost.
• Propulsion: Tendon recoils, adding power the muscle alone could not have produced at that speed (Bosco & Komi, 1979).

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Tendon adapts more slowly than muscle. Muscular strength changes can be measured within weeks, whereas meaningful changes in tendon stiffness and cross-sectional area typically take months of consistent loading (Kubo, 2007). This asymmetry is the single best argument for the extensive base at the bottom of Figure 4: The low-amplitude, high-contact work is not filler, it is the stimulus tendon actually responds to.

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Contact time as the master variable

If you only classify drills by one variable, classify them by ground contact time. It determines which physiological system dominates, how much fatigue accumulates per contact, and what the drill will transfer to.

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Contacts under roughly 0.15 seconds sit firmly in the elastic and reflexive domain (Flanagan & Comyns, 2008). There is not enough time for a large voluntary contribution, so what you are training is the pre-activation of the muscle before landing, the stretch reflex, and the mechanical properties of the tendon. Contacts beyond about 0.30 seconds have moved into concentric territory: The athlete is essentially performing a fast single-leg jump, and strength qualities dominate.

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• Short contact, under 0.15 s Pogos, speed bounds, line hops, low hurdle hops. Trains stiffness and reflexive response. Fatigues the nervous system before it fatigues the muscle.
• Moderate contact, 0.15 to 0.25 s Alternate bounds, single-leg repeat hops, low box work. The mixed zone where most transfer to acceleration lives.
• Long contact, over 0.25 s Standing broad jumps, heavy sled-resisted bounds, deep-landing work. Trains concentric force and eccentric tolerance rather than elasticity.

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Classifying horizontal plyometric drillsA four column table classifying eight drills by ground contact time, limb demand, dominant direction and relative intensity.Classifying horizontal plyometric drillsContact timeLimb demandDirectionRelative intensityPogo hopVery short, under 0.15 sDoubleVerticalLowLine hop seriesVery shortDoubleMixedLowStanding broad jumpLong, single effortDoubleHorizontalModerateRepeat broad jumpModerate, 0.20–0.30 sDoubleHorizontalModerate to highAlternate boundModerate, 0.18–0.25 sAlternating singleHorizontalHighSpeed boundShort, 0.13–0.18 sAlternating singleHorizontalHighSingle-leg repeat hopShort to moderateTrue singleHorizontalVery highDepth drop to boundShort, reactiveSingle into singleMixedVery high

Figure 3. Two drills can look similar and load the athlete very differently. Classify by contact time and limb demand first, because those two columns decide how much of the drill an athlete can tolerate in a session.

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You do not need force plates to estimate this. A stopwatch and a video camera at sixty frames per second will get you close enough to classify a drill correctly, and the audible rhythm of the contacts tells an experienced coach most of what they need. A crisp double-tap sound means short contact; a dull thud means the athlete is sinking.

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Single-limb asymmetry and what to do about it

Single-leg hopping exposes asymmetry in a way that bilateral testing simply cannot. An athlete can hide a fifteen per cent deficit in a back squat by shifting load onto the stronger side. They cannot hide it in a triple hop for distance.

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The commonly cited threshold in the return-to-sport rehabilitation literature is a limb symmetry index of ninety per cent, meaning the weaker limb should reach at least ninety per cent of the stronger limb’s distance (Noyes et al., 1991). That threshold belongs to clinician-led return-to-sport decisions rather than to general training, and even there it is a screening heuristic rather than a law: An athlete whose stronger limb has also detrained will pass the ratio while remaining objectively weak. Symmetry should therefore always be read alongside an absolute standard, and never treated on its own as clearance.

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The distinction is worth stating plainly, because the two uses of the same test are not interchangeable. What follows is performance coaching: hop testing to find a training deficit in a healthy athlete. Rehabilitation is a different job with different criteria. If the asymmetry sits alongside pain, swelling, a joint that gives way, a recent injury or trauma, a knee or ankle that has been operated on, a concussion, or a strength or hop test already failed in a clinical setting, the progression is not the coach’s to set — it belongs to the clinician managing the case, working to their own return-to-sport criteria (Chmielewski et al., 2006).

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1. Test a single hop for distance on each limb, best of three.
2. Test a triple hop for distance on each limb, best of three.
3. Test a six-metre timed hop on each limb.
4. Compare each limb against the other, and both against a pre-injury or squad-normative absolute value.

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Where a genuine deficit exists, the correction is not simply more hopping on the weak side. It is usually a combination of unilateral strength work to raise the ceiling, isometric and eccentric calf loading to improve tissue tolerance, and only then reactive hopping to restore the elastic quality. Adding reactive volume to a limb that cannot yet tolerate it is how tendinopathies start (Magnusson et al., 2010).

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Programming volume without guessing

Contact counts are the standard currency of plyometric programming, and the numbers in Figure 4 are a reasonable starting frame. They are not prescriptions. A ninety-kilogram second row and a fifty-five-kilogram distance runner do not experience one hundred contacts identically.

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The extensive to intensive loading continuumFive stacked rows describing a progression from high volume low intensity horizontal work at the bottom to very low volume maximal work at the top.The extensive to intensive loading continuumExtensive — 120 to 200 contacts per sessionLow hops, skips, ankling and rhythm work. Contacts are cheap, the tissue is being conditionedrather than challenged, and the athlete can perform this two or three times a week.Extensive to moderate — 80 to 120 contactsDouble-leg horizontal hops, short hurdle series, submaximal bounding for rhythm. Quality stillholds across the whole session.Moderate — 60 to 80 contactsAlternate bounding for distance, repeat broad jumps, low-box work. Rest between sets rises to twoor three minutes.Intensive — 30 to 60 contactsSingle-leg hopping, speed bounds, combination jumps. Every rep is measured or filmed because thepoint of the session is quality, not accumulation.Highly intensive — 20 to 40 contactsDepth drop to bound, maximal single-leg speed bounds, weighted bounding. Full recovery betweensets, and never on the same day as a heavy maximal-strength session.Rising intensityFalling volume

Figure 4. Volume and intensity move in opposite directions. Early season work sits low on this stack with many contacts and modest intensity; competition-phase work sits high with very few contacts at near-maximal quality.

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Three adjustments make the counts usable. First, weight the contacts by intensity rather than counting them equally; a depth drop to bound is worth several pogo hops. Second, count only the contacts that occurred at the intended quality, which in practice means stopping the set when distance per bound drops by more than about five per cent. Third, treat single-leg hopping as double-cost per limb relative to alternating work.

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Frequency matters as much as volume. Two well-placed sessions a week with adequate spacing will produce more adaptation than four sessions crammed around heavy lifting, because the connective tissue needs the interval. Placing intensive plyometrics on the same day as heavy lower-body strength work is defensible if the plyometrics come first and the volume is small; placing them the day after is usually a mistake.

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A useful rule of thumb: If you cannot say out loud what quality a given drill is training and roughly what its contact time is, it does not belong in the session yet.

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Turning bounding into a test

Bounding becomes far more useful when it is measured. The standing triple bound and the ten-bound test for distance are both simple, repeatable, and sensitive to changes in horizontal power (Maulder & Cronin, 2005).

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The protocol only works if it is standardised. Fix the starting position, fix whether the first contact counts, fix the surface, fix the footwear, and fix the number of bounds. Distance covered in ten bounds from a two-foot start is a completely different measurement from distance in ten bounds from a three-step run-in, and comparing them will tell you nothing.

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• Standing triple bound: From a two-foot start, three bounds, measure to the rear heel of the landing.
• Ten-bound test: Same start, count ten contacts, measure total distance.
• Single-leg triple hop: Three hops on one limb, measure and compare sides.
• Bound index: Total distance divided by number of contacts, which controls for athletes who simply take more, smaller bounds.

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The bound index is worth highlighting. Two athletes can cover twenty-five metres in ten bounds, one with long, floating contacts and one with short, choppy ones. Dividing distance by contacts, and separately noting total time, distinguishes them. The athlete with a high index and a low time is the one whose horizontal power is genuinely improving.

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Putting it into a programme

The following twelve-week structure assumes a healthy athlete with a reasonable strength base, training three to four times a week, with horizontal plyometrics appearing twice weekly.

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Weeks one to four: Build the spring

Sessions consist of ankling, pogo hops, line hops and low double-leg horizontal hops. Total contacts sit between one hundred and twenty and one hundred and eighty per session. Nothing is measured for distance yet; the entire focus is rhythm, a quiet landing, and a foot that does not collapse.

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• Pogo hops: 4 sets of 20, focus on minimal knee bend.
• Line hops forward and back: 4 sets of 20 seconds.
• Ankling for 20 metres: 4 repetitions.
• Double-leg forward hops over low markers: 4 sets of 6.

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Weeks five to eight: Introduce horizontal projection

Standing broad jumps and repeat broad jumps enter, alongside skipping for distance as the direct precursor to bounding. Contacts drop to between eighty and one hundred and twenty. This is the first block where distance is recorded.

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• Standing broad jump: 5 singles, measured, full recovery.
• Repeat broad jump: 4 sets of 3.
• Skip for distance: 4 repetitions over 30 metres.
• Continue one ankle-stiffness drill as a warm-up carry-over.

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Weeks nine to twelve: Bounding and single-leg work

Alternate bounding for distance appears, then single-leg hopping in small doses. Contacts fall to between forty and seventy, rest rises to three minutes between sets, and every set is either measured or filmed.

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• Alternate bounds over 20 to 30 metres: 4 to 6 repetitions.
• Single-leg triple hop: 3 per limb, measured.
• Speed bounds over 20 metres: 3 repetitions, emphasis on turnover.
• Ten-bound test at the end of week twelve as the block outcome measure.

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Two housekeeping rules apply across all three blocks. Perform this work on a forgiving but firm surface such as a track, a firm grass field, or a sprung floor; deep sand and thick mats remove the elastic stimulus entirely, and concrete removes the margin for error. And place the session early in the week when the athlete is fresh, because reactive quality is the first thing fatigue removes.

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Sport applications

Sprinters and jumpers use bounding as a direct competition-specific exercise rather than as general preparation. For a long jumper the bounding rhythm is close to the event itself, so amplitude and take-off angle are coached precisely.

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Field-sport athletes in football, rugby, hockey and soccer benefit most from the moderate-contact zone. Alternate bounding and single-leg hopping improve the ability to accept load on one limb at speed, which is exactly what happens on a hard cut or a decelerating step.

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Court-sport athletes should bias towards lateral and multidirectional hopping alongside the straight-line work, because their exposure to sideways loading is far higher than a sprinter’s.

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Combat-sport athletes gain less from long-amplitude bounding and more from short, stiff, low-amplitude hopping, which reflects the small, fast footwork adjustments that dominate their sport.

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Common mistakes

• Starting at stage four. Introducing alternate bounding for distance before the athlete can hold a stiff ankle through twenty consecutive pogo hops. This is the direct cause of most shin and calf complaints attributed to plyometrics.
• Chasing distance instead of quality. Distance per bound falls as fatigue rises. Continuing the set past that point trains a slower, sloppier pattern and adds injury exposure for no adaptive return.
• Treating hops and bounds as interchangeable. Thirty hops on one leg is roughly double the per-limb exposure of thirty alternating bounds. Programmes that use the terms loosely routinely double an athlete’s intended load.
• Bounding on the wrong surface. Sand and thick mats absorb the elastic energy the drill exists to train. Concrete provides the stimulus but leaves no margin for a poor landing.
• Placing intensive plyometrics after heavy lifting. Reactive quality is fatigue-sensitive. Once the athlete is tired, they are practising a degraded version of the skill.
• Ignoring the arms. Bounding rhythm is driven substantially by arm action. An athlete with passive arms will produce a shorter, flatter bound regardless of leg strength.
• Using symmetry ratios without absolute standards. A ninety per cent limb symmetry index means nothing if both limbs have detrained. Always pair the ratio with an absolute benchmark.
• Adding volume rather than intensity when progress stalls. Horizontal plyometrics improve through better contacts, not more of them. If the bound index is flat, the answer is usually strength work or more rest, not another set.

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Coaching cues

• "Push the ground behind you" produces better horizontal projection than "jump forward".
• "Stiff ankle, quiet landing" for stage one and two work.
• "Cycle the leg through" to stop athletes reaching for the ground with a straight leg.
• "Drive the opposite arm" to restore rhythm when bounds become short and choppy.
• "Tall through the hips" to prevent the collapse that lengthens contact time.
• "Same rhythm, more distance" when the athlete speeds up rather than lengthens.
• "Land under yourself, not in front of yourself" to reduce braking forces.
• "Finish the last bound as well as the first" as the quality control for the set.

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FAQs

How many bounding sessions a week should I do?

Two is enough for almost everyone. Connective tissue adapts on a slower timescale than muscle, and the interval between sessions is part of the stimulus. A third session is only worth adding if it is extensive, low-amplitude work placed well away from the intensive days.

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Is bounding safe for a beginner?

Stage one and stage two work is safe for most healthy beginners. True alternate bounding for distance is not a beginner drill. The gate is not age or training age in the abstract; it is whether the athlete can hold a stiff ankle for twenty consecutive low hops and land quietly on one leg from a small step. If they cannot, they are not ready.

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Do I need to be able to squat a certain multiple of bodyweight first?

The idea that you must squat one and a half times bodyweight before doing plyometrics is a widely repeated rule of thumb rather than a well-supported threshold. Strength helps and a stronger athlete generally tolerates more, but the more relevant question is whether the athlete can control a single-leg landing (Wisløff, 2004). Use the landing test, not the barbell.

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Why do my shins hurt after bounding?

Almost always volume progressed faster than tissue tolerance, often combined with a hard surface and worn footwear. Reduce contacts sharply, return to low-amplitude work, and rebuild over several weeks. Persistent or localised bone pain warrants assessment by a clinician rather than a training adjustment, because it can indicate a bone stress injury.

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Should I bound in spikes or trainers?

Trainers with a firm midsole for the general preparation phase, and spikes only for advanced athletes doing event-specific work on a track. Spikes increase the stiffness of the interaction with the ground, which raises both the stimulus and the loading rate.

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How do I know if I am improving?

Track the ten-bound test and the bound index rather than how the session felt. Improvement shows up as more distance for the same number of contacts, or the same distance in less time. Both are meaningful; the second is usually the one that transfers to sprinting.

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Can I do horizontal plyometrics if I have had an ACL reconstruction?

Hopping is a standard part of late-stage rehabilitation and return-to-sport testing, but the timing and the progression must be set by the clinician managing the case. Do not self-prescribe a bounding programme after a knee reconstruction; the criteria for progressing between stages are specific to the individual and to the surgical procedure.

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Is bounding better than sprinting for getting faster?

No, and it is not a substitute. Sprinting is the most specific stimulus for sprinting. Bounding is a supplementary means of loading the horizontal, single-limb elastic qualities that sprinting relies on, in a form that allows more targeted overload than sprinting alone.

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Recommended videos

Each video below was chosen because it covers a specific part of this article in more depth than text alone allows.

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Related reading on FitXplor

• 3.1 Introduction to Plyometrics
• 3.2 The Stretch-Shortening Cycle
• 3.3 Landing Mechanics and Force Absorption
• 3.4 Sprint Mechanics and Maximum Velocity
• 3.8 Jump Training and Vertical Power
• 3.9 Reactive Strength and Elastic Qualities
• 3.6 Acceleration: Mechanics, Physiology, and Programming
• 4.3 The Foot and Ankle Complex

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References

Bosco, C., Komi, P.V. (1979). Potentiation of the mechanical behavior of the human skeletal muscle through prestretching. Acta Physiologica Scandinavica.

Cavagna, G.A. (1977). Storage and utilization of elastic energy in skeletal muscle. Exercise and Sport Sciences Reviews.

Morin, J-B., Edouard, P., Samozino, P. (2011). Technical ability of force application as a determinant factor of sprint performance. Medicine & Science in Sports & Exercise.

Rabita, G. et al. (2015). Sprint mechanics in world-class athletes: a new insight into the limits of human locomotion. Scandinavian Journal of Medicine & Science in Sports.

Lockie, R.G. et al. (2014). Relationships between unilateral horizontal and vertical jump tests and sprint performance. Journal of Human Kinetics.

Kubo, K. et al. (2007). Effects of plyometric and weight training on muscle-tendon complex and jump performance. Medicine & Science in Sports & Exercise.

Roberts, T.J., Azizi, E. (2011). Flexible mechanisms: the diverse roles of biological springs in vertebrate movement. Journal of Experimental Biology.

Flanagan, E.P., Comyns, T.M. (2008). The use of contact time and the reactive strength index to optimize fast stretch-shortening cycle training. Strength and Conditioning Journal.

Maulder, P., Cronin, J. (2005). Horizontal and vertical jump assessment: reliability, symmetry, discriminative and predictive ability. Physical Therapy in Sport.

Noyes, F.R., Barber, S.D., Mangine, R.E. (1991). Abnormal lower limb symmetry determined by function hop tests after anterior cruciate ligament rupture. American Journal of Sports Medicine.

Wisløff, U. et al. (2004). Strong correlation of maximal squat strength with sprint performance and vertical jump height in elite soccer players. British Journal of Sports Medicine.

Magnusson, S.P., Langberg, H., Kjaer, M. (2010). The pathogenesis of tendinopathy: balancing the response to loading. Nature Reviews Rheumatology.

Chmielewski, T. L., Myer, G. D., Kauffman, D., & Tillman, S. M. (2006). Plyometric exercise in the rehabilitation of athletes: Physiological responses and clinical application. Journal of Orthopaedic & Sports Physical Therapy, 36(5), 308–319. Read on PubMed