Deep divefrom Episode 13Training12 November 202618 min

Does Sprinting With a Parachute Make You Faster?

A deep dive into one paper: what was known before, what the researchers did, what the numbers say and what they don't.

The paper: Parachute-resisted sprint training: systematic review with GRADE

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Transcript

The script the two AI voices read from. The times are worked out from the script, not heard, so a line can start a few seconds early or late.

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Cold open

Host 1If a sprinter runs with a little parachute flapping behind them, how much does it actually slow them down?

Host 2Where it was measured cleanly, by about three and a half to six percent. And the honest summary of seventeen studies is that it seems to help some sprint times, but the evidence is low to very low in certainty.

Host 1Welcome to the Hastrup Review of Science, where artificial intelligence reads real science, so you don't have to pretend you understood the paper.

Host 2Today, one paper: a systematic review of parachute-resisted sprint training, published in Sports Medicine Open. It pulls together everything researchers have measured on running with a drag chute, and grades how much we can trust it.

Why slow a sprinter down

Host 1Why would anyone want to make running fast harder on purpose, rather than just running fast a lot?

Host 2Because of overload, the oldest idea in training. You get stronger by lifting a bit more than is easy, and coaches have long wanted the same for sprinting itself, not just in the weight room.

Host 2The wider picture in the field is that sprinting, especially the start, is about pushing the ground backwards hard. Add resistance, and every step has to push harder for longer, which is the quality coaches want to grow.

Host 1So what are the usual ways of adding that resistance, and where does a parachute fit in among them?

Host 2The paper lists sled towing, sled pushing, weighted vests, uphill sprints, elastic bands, and parachutes. The parachute is the odd one out: the resistance comes from air drag, not from a fixed weight.

Host 1Is that a practical difference or a technical one, for a coach standing on a field?

Host 2Both. A parachute is cheap, light, and fits in a bag, which is why it is popular. But its pull changes with how fast you run, how big the canopy is, how it opens, and how the wind blows, so you never know exactly how heavy the load is.

What was known before

Host 1Before this review, what did people already believe about parachute training?

Host 2That it clearly slows you down in the moment, and that it might make you faster over weeks. Individual studies existed on both questions, but they used different athletes, different parachutes, different distances, and different comparisons.

Host 1When you say different comparisons, do you mean some studies had no fair comparison group at all?

Host 2Yes, exactly. Some compared parachute training with the same amount of ordinary sprinting, which is fair. Others only measured one group before and after, so any improvement could just be normal training, the season, or getting used to the test.

Host 1And in sports science, is there also a worry that running with drag spoils your technique?

Host 2That is the classic worry, and the paper treats it carefully. Its point is that a slower, more leaning stride under resistance looks like the early part of a normal sprint, so being different from top-speed running is not automatically bad technique.

The open question

Host 1So what was the open question this group set out to answer?

Host 2Two questions, kept deliberately apart. First, what does a parachute do to a sprint while you are towing it. Second, does training with one for weeks make you faster without it.

Host 1Why does it matter to keep those two questions separate, rather than lumping all the studies together?

Host 2Because a parachute slowing you down today says nothing about whether you will be faster in a month. The authors stress that an acute slowdown is not evidence that the training works.

How they did it

Host 1Now I want to understand how they actually did this. What does a systematic review mean in practice?

Host 2It means writing down the rules before looking, then searching every relevant database and keeping every study that fits. Here they registered the plan in advance on the Open Science Framework, so they could not quietly change the rules later.

Host 1Which databases did they search, and how many records did that turn up?

Host 2Four: PubMed, Scopus, Web of Science, and SPORTDiscus, searched on the seventeenth of May twenty twenty-six. That gave three hundred and three records, two hundred and sixty-eight of them from SPORTDiscus alone.

Host 1Three hundred records down to seventeen studies sounds like a big funnel. Where did they all go?

Host 2Twenty-eight were duplicates and two hundred and twenty-five were off topic at the title stage. Of fifty they wanted to read in full, nineteen could not be retrieved, and twenty-one more failed the rules, while checking reference lists found seven extra studies.

Host 1Wait, nineteen studies simply could not be found? Is that unusual, and could it bias the answer?

Host 2It is a noticeable gap, and the paper reports it plainly rather than explaining it away. We cannot know what those nineteen reports said, so it is one more reason to hold the conclusions loosely.

Host 1What counted as a study they would keep?

Host 2Healthy people of any age, sex or level, from school pupils to elite players, with parachute sprinting as a distinct condition. If a study mixed parachutes with sleds and you could not separate the parachute's effect, it was out, at least for that comparison.

Host 1Did they then combine all the numbers into one overall figure, the way you hear meta-analyses do?

Host 2No, and they explain why. The protocols, comparison groups and measurements differed so much, and so many studies did not report the spread of their data, that a pooled number would have been misleading. So they did a structured summary study by study, following a reporting guideline called SWiM.

Host 1How did they judge whether each individual study was any good?

Host 2With a scoring checklist called the Modified Downs and Black, which asks things like whether the aims are clear, whether groups were randomized, and whether the sample was big enough. Four studies came out high quality, ten fair, and three low.

Host 1And then the GRADE part from the title. What is GRADE, in plain words?

Host 2GRADE is a widely used system for saying how much you can trust a body of evidence on one question. Each outcome is rated high, moderate, low, or very low, and a rating drops for weak study design, inconsistent results, indirect evidence, imprecision, or suspected missing studies.

Host 1Does a randomized trial automatically start with a better grade than other studies?

Host 2Yes. Randomized evidence starts at high and gets marked down for problems, while non-randomized evidence starts at low. So a single randomized study can carry more weight than several uncontrolled ones.

Host 1Who was actually in these studies, what kind of athletes?

Host 2Sprinters, college track athletes, rugby players, youth and adult football players, baseball and cricket players, recreational female sprinters, students, and in one case a single man. The acute studies were small, often between seven and eighteen people.

What a parachute does to one sprint

Host 1Let's start with the in-the-moment results. Just how much does the parachute slow someone down?

Host 2Eight acute studies all agreed on the direction: slower velocity, longer times. The three that reported clean numbers found drops of about five percent in men and six in women in one study, about four and a half percent in another, and three point four percent in top speed in a third.

Host 1Is a five percent slowdown a lot or a little, compared with other kinds of resisted sprinting?

Host 2It is on the mild side. As a rough wider picture, coaches using heavy sleds often aim for slowdowns of twenty to fifty percent or more, and the paper itself cites work with drops of twenty to sixty percent. A parachute, as tested here, is a light touch.

Host 1Does a bigger parachute simply mean more slowing?

Host 2Broadly, yes, larger canopies gave larger velocity drops and bigger changes in force. One lab study tested three sizes, from point three nine to point seven two square metres, with fifteen male sprinters.

Host 1And what did that lab study find about how hard the runners pushed the ground?

Host 2Every parachute size increased the backward push into the ground, what they call horizontal force and impulse, compared with free sprinting. The small and medium chutes differed from each other, but medium and large did not, and only the large one reduced braking at each footstrike.

Host 1So if I have this right, a parachute makes each step a bit more of a push, and past a certain size you do not get much more push for the extra canopy?

Host 2That is a fair reading of that one study, with a caveat: it is fifteen sprinters in one lab. It suggests a plateau between medium and large, not a rule.

Host 1What happens to the shape of the stride when you are towing one?

Host 2With light resistance, several studies saw little change in stride length, stride rate, or ground contact. With more resistance, contacts got longer, steps shorter, and the trunk leaned further forward, though the size and even direction of these changes varied between studies.

Host 1I have seen athletes run with a parachute and then release it mid-sprint. What did the studies say about that?

Host 2That is called resist-and-release. In one study of ten university athletes, the push in the steps just after release dropped sharply compared with the last towed steps, so the release itself is a moment of real disturbance.

Host 1Did anyone measure what the muscles were doing, or how much energy it costs?

Host 2Two small studies, twenty-four people in total. In elite under-seventeen footballers, the hamstrings and glutes worked about as they do in normal sprinting, with slightly more thigh-front muscle, and the energy cost was higher.

Host 1And the second of those two muscle studies?

Host 2Seven amateur rugby players on a special treadmill, testing three parachute sizes. Muscle activation did not differ between sizes, but bigger chutes raised peak power and lowered top speed step by step.

A word from our sponsor

Host 1This episode is brought to you by Softland, the parachute for toast.

Host 2I was a sceptic. Then my toast began descending three point four to six percent slower than unresisted toast.

Host 1Softland deploys on the edge of the table, and lands every slice butter side up, as confirmed in a sample of one kitchen.

Host 2I upgraded to the large canopy. The braking impulse is gone, and so, frankly, is breakfast.

Host 1For best results, use resist-and-release, letting go of the toast just before it reaches the floor.

Host 2My slice from March is still coming down over the kitchen. Certainty of the evidence: very low. Certainty of lunch: also very low.

Host 1Softland. Some things are better late.

Weeks of training: does it make you faster

Host 1Now for the question that matters to most people. Does training with a parachute for weeks actually make you faster?

Host 2The short answer: possibly, for some sprint distances, and nobody can yet say whether it beats ordinary sprinting. Nine training studies lasted from four to twelve weeks, at one to three sessions a week, and most reported improvements.

Host 1Which of those nine studies is the most convincing, and what exactly did it do?

Host 2A randomized study of sixteen track sprinters from twenty eleven. One group trained three times a week for four weeks towing a large parachute over thirty and fifty metres, and the other did the identical sessions without one.

Host 1That sounds like a fair test. What did the parachute group gain?

Host 2They improved over zero to ten, ten to twenty, and zero to twenty metres, and also in top speed and the forty to fifty metre stretch. Their gains in early acceleration were larger than those of the group running free.

Host 1So in the single fairest comparison, the parachute did a bit better at the start of the sprint?

Host 2Yes, that is the right way to put it, and note the size of the evidence: one trial, sixteen people, four weeks, fifteen years ago. It is a hint, not a settled answer.

Host 1The abstract mentions bigger-sounding numbers, a three point four eight percent gain and over half a second in the hundred metres. Where do those come from?

Host 2The three point four eight percent was a sixty-yard sprint in under twenty-three baseball players, but their programme combined sleds, parachutes, strength work and jumping. So nobody can say how much of it was the parachute.

Host 1And the half second in the hundred metres, nought point six one eight seconds?

Host 2That came from a group of five male students in a school athletics programme, whose average hundred metres went from about thirteen point four to twelve point eight seconds over roughly five weeks. The parachute size, frequency and number of runs were not even reported.

Host 1Five people and no description of the training. Why would a review include something that thin at all?

Host 2Because a systematic review is meant to show everything that exists, then grade it honestly. Including it is not endorsing it, and the study's weakness shows up in the low ratings.

Host 1When untrained students get faster over five weeks, how do we know it was the parachute and not simply training at all?

Host 2We mostly do not. The paper says plainly that improvements in the uncontrolled studies cannot be attributed to the parachute, and that mixed programmes cannot be credited to it either.

Host 1What about top speed, the bit at the end of a hundred metres?

Host 2Very thin. Most studies never measured top speed directly; they inferred it from overall times over longer distances, which blend acceleration and top speed together.

How sure can we be

Host 1So how did GRADE score all of this in the end?

Host 2Low at best. The acute slowdown and the long-term gains in acceleration and short sprints were rated low, and everything else, including mechanics, muscles, top speed, differences between groups of athletes, and the best parachute size, was rated very low.

Host 1Low sounds harsh for something every study agreed on. What does a low rating actually mean for me as a listener?

Host 2In GRADE terms, low means the true effect may be substantially different from what the studies suggest. Even the slowdown, which everyone saw, rates low because the studies were small and the load so poorly described.

Host 1Very low, then, means what?

Host 2That we have very little confidence in the estimate. Better studies could easily reverse it.

What it means and for whom

Host 1So what is the principle a coach or a keen runner should take from this?

Host 2That a parachute is a cheap, portable way to make sprinting a little harder, and it may help acceleration. The paper says it should be one part of a speed programme, alongside free sprinting, technique work and strength training, not a replacement.

Host 1If I coach a youth football team with no budget, is this worth buying?

Host 2It is reasonable as a variation, and the paper notes it suits settings without sleds or labs. What the evidence does not show is that it beats the same amount of normal sprinting.

Host 1Does the paper give coaches any warning signs to watch for while athletes use one?

Host 2Yes: overstriding, heavy braking, unstable posture, or a broken stride rhythm suggest the resistance is too high or poorly controlled. Where possible, coaches should time splits or film runs to check how much the athlete is slowing.

Host 1Does this tell us anything for women, children, or elite sprinters specifically?

Host 2Very little. Female, youth and elite data were sparse, and no study was designed to test whether the effect differs by sex, age, sport, or level.

Host 1What should we definitely not conclude from this review?

Host 2That parachutes make you faster than ordinary sprinting, that there is an ideal parachute size, or that the in-the-moment slowdown proves the training works. None of those is supported.

Honest caveats

Host 1What are the weak spots of the review itself, beyond the weak studies it collected?

Host 2Nineteen reports could not be retrieved, and only seventeen studies made it in. Without pooling, the sizes of the effects could not be compared consistently across studies.

Host 1Is there a problem with how the parachute load itself was described?

Host 2That is the central problem. Many studies reported only the canopy dimensions, without how much the runner actually slowed, the drag force, or the wind, so you cannot compare one study's parachute with another's.

Host 1Was there anything unusual in how the paper itself was put together?

Host 2One thing worth knowing: the authors disclose that they used a chatbot to help polish the language and organise text. They state it did not pick studies, grade them, or analyse data, and that they checked all of it.

What to watch next

Host 1What would a study need to look like to actually settle the question?

Host 2Larger samples, a proper comparison group doing the same sprints without a parachute or with a sled, and the load reported as the slowdown it causes and, ideally, the drag force. Top speed should be measured directly, with split times over several phases of the sprint.

Host 1And are there specific groups they say researchers should study next?

Host 2Female athletes, young athletes, elite sprinters and specific sports. Until then, a sensible question to ask of any new parachute study is simple: compared with what, and how much did it slow them down?

Sign-off

Host 1That is the deep dive for this week. If you want the week's new papers instead of one, every weekend this same feed carries the roundup, the week's new papers in one short episode.

Host 2Thanks for listening, and if you try a parachute, check the wind first.