Best Practices for Resisted Sprint Training for Acceleration and Maximum Velocity
What All Coaches Need to Know About Resisted Sprints Training
Resisted sprint training involves sprinting against an added resistance – such as pushing a sled, running uphill, or using resistance bands – to increase a sprinter’s power output. Coaches primarily use this method to target improvements in acceleration (particularly the first 20m of a sprint) and sometimes maximum velocity (top sprinting speed). Research and coaching practice suggest that resisted sprints can enhance an athlete’s ability to apply horizontal force, leading to faster starts and potentially higher speeds.
This report compiles evidence-based best practices for resisted sprints across all levels (youth, developing, elite), covering optimal loading, distances, training volume, periodisation, tools, and applications beyond sprinters. Where the science is inconclusive or coaches disagree, we highlight the debates and encourage weighing the pros and cons in context.
Optimal Resistance Load
Selecting the right resistance load is critical. Too little load may not provide extra stimulus, whereas too much can drastically alter running mechanics. Researchers often define load in terms of how much it slows the sprinter’s velocity. Loads are classified roughly as light (causing <10% velocity decrement), moderate (10–15%), heavy (15–30%), and very heavy (>30% slower than normal sprint) (Alcaraz, 2009; Haugen et al., 2019). For example, a light load might be a sled weight so small that the athlete runs at ~90% of usual speed, whereas a very heavy load might cut their speed in half.
Key considerations on what is the optimal load for your athletes include:
Acceleration Training vs. Maximum Velocity Training: Lighter resistances (e.g. ~10% velocity loss) tend to preserve form and are thought to better target top-speed mechanics, whereas heavier loads (30% or more velocity reduction) provide a bigger strength stimulus for improving the acceleration phase (Curry, 2025).
A recent study on youth footballers found both heavy (~75% velocity reduction) and light (~25% reduction) sled training improved sprint performance, but heavy loads gave slightly greater gains in the acceleration phase, while lighter loads more strongly improved maximum velocity (Baena-Raya, 2025). This supports the idea of matching the load to the desired outcome (forceful acceleration vs. pure speed).“Optimal” Load Debate: Traditionally, many coaches limited sled loads to keep speed loss under ~10% or limit load weight to 10% of the athlete’s body weight to avoid the risk of adversely affecting running technique. However, some sports scientists argue for much heavier loads to maximize power output. There is some evidence that the optimal load for maximising power adaptations may be when sprint velocity is reduced by ~50% (Bolger et al., 2015; Cross, 2017). Very heavy sled pulls dramatically increase horizontal force output, but studies warn that this may yield only trivial extra gains in actual sprint times compared to lighter training. What is beneficial for initial steps (high force) is not necessarily beneficial for overall 100 m performance. Thus, no single “optimal” load works for all purposes – it depends on whether the focus is on pure acceleration strength or maintaining sprint mechanics and speed.
Technique Considerations: Heavier resistance causes noticeable changes in form – more forward lean, longer ground contact times, and shorter stride lengths. Some coaches worry this could ingrain bad habits. Interestingly, a review of 11 studies found no conclusive evidence that heavy sled training harms sprint times; in fact, studies with heavy or very heavy loads often showed improvements in sprint performance (Petrakos, 2016). The acute changes in mechanics might actually provide a specific overload that leads to better technique when unresisted, akin to how lifting heavy weights improves jump performance even though the movement is different. Coaches have addressed form concerns by using a mix of training – pairing heavy resisted sprints with unresisted sprints to immediately practice good mechanics at high velocity. This “contrast” approach lets athletes experience a heavy push and then reinforce proper technique in the same session.
Individual and Developmental Differences: Load selection should consider the athlete’s training and developmental level. Youth and novice sprinters may benefit from erring on the lighter side or using alternative resistance like gentle hills, so they can learn correct sprint mechanics without excessive strain. Very heavy loads are generally not recommended for young athletes who have not fully developed coordination and strength. However, a study on developing youth (mid-puberty and older) showed sled towing twice per week with moderate loads was effective, increasing horizontal force and step frequency without harming speed (Rumpf et al., 2014).
Elite sprinters, who are stronger and technically proficient, can tolerate heavier loads and use a range from light to very heavy strategically. Notably, top sprint groups differ in approach: UK Athletics advocate using only light resistances to ensure mechanics remain fluid, whereas some elite Jamaican sprinters (e.g. former 100 m world record holder Asafa Powell) have successfully used very heavy sled pulls in training (up to 100% of bodyweight) (Lee, 2011). This illustrates that coaches must evaluate what their athletes can handle – monitoring whether a given load is producing the desired adaptation without undue loss of form.
Key Takeaway for Coaches: Most practitioners aim for a load that significantly challenges the sprinter’s acceleration yet still allows a reasonably upright posture and rapid stride rate. In practice this often corresponds to roughly 10–30% of body mass on a sled (or a load causing ~5–30% speed decrement), adjusted up or down based on the athlete’s strength and the goal of the session. Heavier loads bias the training toward horizontal force development (helping the drive phase), while lighter loads or free sprints bias velocity and technique. Given the ongoing debate, many coaches use a range of loads over a training cycle, rather than sticking to one absolute “optimal” resistance. The key is to ensure the athlete is running hard against the resistance (not just trudging) and that the loading aligns with their training focus for that phase.
Suggested Distances for Resisted Sprints
Resisted sprints are typically performed over short distances, especially when targeting acceleration. The added load slows the athlete, so the effective portion of the sprint is the early drive phase. Best practices for resisted sprint distances include:
Short Accelerations (5–20 m): For developing acceleration, coaches usually keep resisted runs very short. Distances of about 5 m to 20 m are common for sled pulls or uphill sprints when using substantial resistance. Over these distances the sprinter can apply maximal force in each step without the resistance causing excessive deceleration or fatigue. Research supports using high loads for very short sprints: for instance, heavy sled towing is effective for improving 5–10 m sprint performance (initial explosion). Athletes often accelerate for ~10–15 m with a heavy sled, then stop once the benefit of the overload has been realised in those initial steps.
Longer Sprints and Top-Speed Work: To target maximal velocity with resistance (which is less common), the load must be light. If the goal is to slightly overload the speed phase (30 m+), tools like small parachutes or very light sleds can be used for 20–40 m sprints. These provide a mild resistance so the runner can still approach top speed. For example, a sled load causing only ~5–10% speed loss might be used over 30 m to challenge the athlete’s mechanics at near-max velocity. However, many coaches find that unresisted or even assisted sprints are superior for developing top speed, since maximal velocity improves most when athletes can run at 95–100% of their natural pace. Thus, resisted runs beyond ~30 m are relatively rare; if included, they usually involve a flying start (to get up to speed) with a light resistance over the flying zone to slightly tax the sprinter’s high-end speed endurance.
Uphill Sprint Distances: Uphill sprints (a form of natural resistance) also tend to be short. Commonly, 10–30 m uphill dashes are used. The incline provides resistance mainly in the acceleration phase and sprinters usually cannot maintain explosiveness much beyond 20–30 m uphill. Studies in team-sport athletes show uphill sprinting, like sled pulls, effectively improves acceleration ability. Coaches often programme hill sprints in the off-season for 20–30 m to build strength and explosiveness out of the blocks.
Key Takeaway for Coaches: In sprint training, distance is intimately tied to the phase of the race being trained. Since resisted sprints principally train the acceleration and transition phase, they are kept to short distances that mirror those phases. A useful guideline is to resist only the portion of the sprint that benefits from extra force production. For pure acceleration gains, 5–15 m bursts may suffice; for late acceleration into upright running, 20–30 m with lighter resistance can be used. If an athlete attempts a heavy resisted run over too long a distance, they will slow dramatically and the later part of the sprint becomes unproductive (or reinforces a slow, plodding rhythm). Therefore, coaches should select a distance where the sprinter can maintain explosiveness throughout. For most, this means resisted efforts are kept well under 50 m – typically in the 10–30 m range – whereas longer sprints (30–60+ m) are left unresisted or use assistance to train max velocity.
Recommended Sets, Repetitions, and Recovery
Resisted sprints are high-intensity, neuromuscular efforts. As such, they should be done in low volumes with ample recovery, similar to unresisted sprint training. Key recommendations for structuring sets and reps are:
Repetitions per Set: Because each sprint should be near-maximal effort, athletes can only do a limited number before fatigue impairs performance. A general guideline is 4–8 sprints per set for heavy resisted runs, or up to perhaps 8–12 for lighter resisted runs. In practice, a coach might have an athlete do 5 or 6 × 10 m sled pulls (heavy) or 8 × 20 m sled runs (moderate) in one session. One coach reported that with an 80% of max sled load (very heavy), sprinters could maintain their 0–20 m performance for about 5–8 repetitions, whereas with a lighter 30% load they could do 10–12 quality reps before slowing down. Once an athlete’s speed noticeably drops off, continuing to sprint is less useful, so stop the set when quality declines.
Number of Sets: Sprint training typically involves multiple sets to allow recovery and repeat quality work. For resisted sprints, 1–3 sets of high-quality reps is usually sufficient, depending on the training phase. For example, a session might be 2 sets of 5 × 15 m sled pulls (with several minutes rest between sets). Total resisted sprint count might range from ~6 reps (for a heavy session) up to perhaps 15–20 total reps (in a session emphasizing lighter resisted runs or a mix of resistances). Volume should also consider the distance; longer resisted runs (20–30 m) mean fewer total reps to avoid excessive fatigue. As a rough reference, a study on youth athletes used total sprint distances of 140–300 m per session (e.g. 10–15 reps of 10–20 m) twice per week and achieved measurable improvements.
Rest and Recovery: Full recovery between sprints is crucial to maintain maximal intensity and proper technique. A common rule of thumb among coaches is 1–2 minutes of rest per 10 m sprint or per second of sprinting. In practice, this means 2–3 minutes (or more) rest after a 10–20 m resisted sprint, and upwards of 5–6 minutes after a 30 m run. Heavier resistance may necessitate slightly longer rest since it induces greater muscular fatigue. The athlete should feel fresh enough each rep to sprint with near-max effort. Between sets, a longer break (5-10 minutes) is advisable. The higher the performance level, the longer the recoveries needed. Coaches should resist the temptation to treat resisted sprints as conditioning; the goal is speed-power development, so each rep must be high quality.
Frequency: To see adaptation, resisted sprint training should be done regularly but not every day (to allow recovery and integration with other training). Studies suggest at least 2 sessions per week for 4–8 weeks are needed to yield significant sprint improvements . In practice, sprint athletes often include 1–2 resisted sessions per week in an acceleration-focused training block. This could be, for example, one heavy sled day and one uphill sprint day per week during a 6-week offseason block. More than two heavy sessions a week is usually not feasible due to the intense strain – if additional sprint days are needed, they would be unresisted or technical work.
Monitoring Quality: Coaches should watch for signs of fatigue such as slowing times, deteriorating form, or reduced power in the strides. The moment an athlete’s performance declines (e.g. they start decelerating before the finish of a rep), it’s a sign to end the set or session. It’s better to do slightly fewer high-quality sprints than too many sloppy ones. Using timing devices for splits or marking how far the athlete gets in a timed interval can help gauge if they are still at peak output each rep.
Key Takeaway for Coaches: Treat resisted sprints like any maximal sprint or power exercise: low reps, high intensity, full rest. A sample session might be 2 × 5 × 20 m heavy sled @ 30% velocity reduction, 3 min rest between reps, 6–8 min between sets. Sprint coaches also often pair resisted and unresisted sprints in a session (e.g. a sled pull followed by an unresisted sprint) – in such cases the total volume of each can be slightly lower since the two exercises complement one other.
Integrating Resisted Sprints in the Annual Plan
When and how to use resisted sprints over a season depends on the athlete’s development phase and competition schedule. Here are general periodisation guidelines:
General Preparation Phase: Resisted sprint training is most commonly heavily used in the off-season or early preparatory phase, when the focus is on building strength, power, and technique without the immediate pressure of competition. During this phase, athletes often perform heavier resisted sprints (sled pulls, uphill runs) to develop the muscular and neural foundations for acceleration. This is the time to tolerate more significant technique variations, since athletes have time to adapt and later convert strength gains into speed. Coaches might plan dedicated acceleration blocks with sled towing or hill sprints 1–2 times per week for several weeks. Volume can be higher in GPP (more total sprints or additional drills) since athletes are not yet peaking. It’s common, for example, to see a sprinter do a cycle of heavy sled work in the winter months to boost their starting power.
Specific Preparation Phase: As the season progresses towards competitions, the training shifts to more specific speed work. In this phase, resisted sprints are still included but with lighter loads or reduced volume, and always complemented by plenty of free sprinting. The goal here is to transfer the off-season strength gains into actual sprint performance. Coaches may use moderate loads (e.g. 10–15% body weight or light uphill gradients) over slightly longer distances, and often employ contrast training – pairing one resisted sprint with one or two unresisted sprints. This method helps athletes convert increased force capability into faster velocities. During pre-comp, resisted sprints might be done once a week or incorporated in mixed sessions. For instance, a workout might include 3 × 20 m sled (moderate load) followed by 3 × 30 m unresisted sprints, with full rest. The resisted element is present, but the emphasis is shifting towards speed and technical refinement.
Competition Phase: In-season, the priority is racing and maintaining peak speed, so resisted sprinting is greatly reduced or omitted for pure sprinters. Elite sprint groups rarely prioritise heavy resistance work during the competitive season. The reason is that heavy resistance can cause soreness, neural fatigue, or slight technique changes that could detract from race performance. Instead, sprinters focus on explosive block starts, relay exchanges, and maximal velocity runs with complete recovery. If resisted sprints are used at all in-season, they are usually very light (to avoid undue fatigue) and used sparingly, perhaps as a * potentiation* tool in training – for example, a couple of light sled runs to fire up the athlete before doing full-speed 30 m sprints. Another scenario is occasional short uphill sprints to keep acceleration strength on point, but these would be low volume. Essentially, once the competitive phase arrives, any resistance training becomes more about maintenance of the power qualities developed earlier, rather than increasing them.
Tapering and Peaking: In the final taper before major competitions, resisted sprints (especially heavy ones) are typically removed entirely to allow the athlete to be fresh and fully adjusted to unresisted sprinting. In the last few weeks, training is high-speed and low-volume. All the resisted work would have been done in prior months, hopefully translating into improved force application when sprinting freely.
Integration with Other Training: Throughout the year, coaches must balance resisted sprint work with strength training and technical work. In periods of heavy sled training, weight room volume might be adjusted down to avoid overloading the same muscle groups. Conversely, if an athlete is doing intensive plyometrics or Olympic lifts, the coach might reduce resisted sprint frequency that week. Many find that treating resisted sprints as a component of the strength/speed program – rather than as pure sprint work – helps periodise it. For example, in a given week of GPP, an athlete might replace one heavy squat session with a sled sprint session. Later in SPP, that sled session might be replaced by pure speedwork on the track. This way, the overall load on the athlete is managed.
Over years, as athletes progress from youth to elite, the emphasis on resisted sprinting can change. The principle is to use resisted sprinting when it addresses a specific weakness (such as lack of early acceleration power), and to back off when that quality is developed or not prioritised in training.
Novice sprinters may spend more time on general skill (learning to sprint properly) and basic strength; heavy sled pulls might appear only briefly, if at all, in their early training years.
Developing athletes (junior or collegiate level) often respond well to phases of resisted sprints to build the specific strength needed for higher-level competition.
Elite athletes tend to use resisted sprints more selectively – they already have a high base of strength, so they might only need short refresher blocks of heavy sled work, or they may use very event-specific resistance (e.g. bobsledders pushing a sled, sprinters doing exactly the amount of resistance that correlates with their block phase).
Key Takeaway for Coaches: Periodise resisted sprints just as you would any other training means: use them to build capacity in the off-season, transition that capacity into specificity in pre-season, and then prioritise pure speed in-season. Both heavy and light resisted sprinting methods have their place, but their timing should align with the athlete’s goals (power development vs. speed expression). Coaches also learn to read their athletes – if resisted work is causing lingering fatigue or hampering technique in a period where sharpness is needed, it’s a sign to reduce or temporarily remove it. On the other hand, if an athlete is lacking explosiveness, adding a short block of sled pulls in the training plan might give them a boost. Effective annual plans often wave the emphasis on resistance: e.g. a 4-week sled phase in GPP, another 2-week mini-phase mid-season if needed, etc., always ensuring it complements the athlete’s racing schedule.
Methods of Resisted Sprinting
There are various tools to provide external resistance during sprinting, each with its advantages and considerations. Coaches can choose based on available equipment and the specific training effect desired.
Weighted Sled Towing
This is the most researched and widely used method. The athlete sprints while towing a loaded weight (plates or sandbags) attached by a harness or waist belt.
Pros: Highly adjustable load – coaches can prescribe a precise weight (e.g. % of loss velocity or body mass). Sled towing directly increases horizontal ground friction, targeting the propulsive force of sprinting. Numerous studies confirm sled training can improve 5–30 m sprint times by increasing horizontal force output.
Cons: If too heavy, sleds may alter running mechanics in a way that coaches do not want, such as excessive forward lean, shorter strides*. Also, the effective resistance depends on surface (sleds slide easier on some tracks than on grass), so the same weight might feel different on different surfaces. Coaches overcome this by using the velocity decrement method (timing the athlete to ensure load is appropriate).
*While often cited as a ‘con’ of weighted sleds, these are technical components of the early phases of acceleration.
Overall, sleds are excellent for pure acceleration training. They require space and a suitable surface, and care that the rope is long enough to not impede the first step. Notably, some elite sprinters use sleds year-round in varying loads (light sled sprints for technique vs heavy for power).
Uphill Sprints
Sprinting up an incline (hill or stadium ramp) is a form of resisted sprinting using body weight against gravity.
Pros: Hills naturally enforce a good acceleration posture (forward lean) and require powerful knee drive. They develop explosive leg drive and horizontal force similar to sleds. Hills are convenient – no equipment needed – and great for group training. They also tend to be lower impact on joints (softer surface, slower speed).
Cons: The slope cannot be fine-tuned easily; too steep a hill can cause suboptimal mechanics (exaggerated forward lean or shuffling). Typically a moderate incline (3–7°) is used for sprint training. Also, top speed cannot be achieved on a hill, so it’s mainly for acceleration.
Many legendary coaches (e.g. Bud Winter, Charlie Francis) incorporated short hill sprints in general preparation to build “speed strength.” Research in team sports shows uphill and sled training produce comparable gains in short sprint performance. Hills should be used with caution for beginners on downhill walks back (to avoid slipping or muscle soreness from eccentric braking).
Resistance Bands and Cords
These include elastic bands or spring-loaded cords attached to the athlete (either held by a partner or fixed to a sturdy anchor) to provide resistance.
Pros: Highly accessible – many coaches or clubs have access to resistance bands. They allow resistance in a small space (even a 10 m area). They can also provide a variable resistance (tension increases as the band stretches), which means the load can increase as the athlete gains speed. This is somewhat opposite to sleds where friction is constant. Bands can be useful for short bursts out of blocks or for multi-directional resisted runs (e.g. a coach holding a band around an athlete’s waist while they sprint in place or over 5 m).
Cons: Harder to quantify the exact resistance (tension depends on band length and how hard the partner pulls). There’s a risk of the band “yanking” the athlete if the partner resistance fluctuates, so smooth coordination is needed. Also, very strong athletes might overpower a simple band, in which case sleds or weighted vests are safer.
Bands are great for younger athletes or in PE settings where you can have partners resist each other in short sprints. Partner towing with a rope or towel is a similar concept – one athlete provides manual resistance. It’s effective in a pinch, but consistency and safety (avoiding sudden release) must be managed.
Parachutes Sprints
A small parachute can be attached to a sprinter’s harness so that as they sprint, wind drag provides resistance. The chute typically expands fully after a few steps and adds drag force proportional to the square of velocity.
Pros: The resistance increases with speed, meaning it is light at the start (not impeding acceleration much) and heavier as the athlete reaches faster velocity. This can be useful for giving a gentle assist in early steps (almost like normal acceleration) and then a load during the speed phase, potentially useful for speed-endurance runs. Parachutes are relatively inexpensive and easy to use on any open field or track.
Cons: They are somewhat unpredictable – a gust of wind can change the resistance or blow the chute sideways. They also introduce slight extra aerodynamic drag which can alter arm carriage or cause the runner to subconsciously adjust form.
Many coaches prefer sleds over chutes for reliability, but parachutes remain popular for variety or when a sled isn’t practical (e.g. on a grass field where dragging a sled is difficult). Chutes are usually kept for longer sprints (30–50 m) with a mild overload, since heavy resistance chutes would be very large and unwieldy.
Weighted Vests or Ankle Weights
Instead of horizontal drag, this method adds weight directly to the athlete’s body. A weighted vest (e.g. 5–10% of body mass) makes the athlete heavier during the sprint, thereby increasing the force needed to accelerate.
Pros: It distributes resistance more naturally (no tether or external device). It can slightly overload the entire sprint motion without requiring any specialized equipment beyond the vest/weights. Weighted vests allow the athlete to sprint with nearly normal mechanics, just with more mass. Research suggests vest loading mainly increases the ground reaction forces; one youth study speculated that a vest might help counteract the loss of leg stiffness seen with sled towing by providing a more vertical load and upright posture.
Cons: Additional weight, if too heavy, can stress joints and alter running kinematics (e.g. heavier landings). It’s harder to quickly shed the resistance (unlike dropping a sled rope). Also, vest loading is limited by practicality – you can’t add huge weight or the athlete simply can’t sprint well.
Vests might be used in short sprints or plyometric drills leading into sprints. Ankle weights are generally discouraged for actual sprinting as they can alter leg recovery mechanics and risk injury; they are more for drills. In practice, weighted vests are less common than sleds or hills for pure sprint work, but some coaches use light vest sprints for an added challenge once a week.
Motorised Resistance Devices
At the elite level, there are high-tech solutions like the 1080 Sprint or other motorised towing systems. These devices can provide a consistent resistance (or even variable/programmed resistance) while measuring speed and force in real time.
Pros: Very precise load control and the ability to adjust resistance throughout the sprint (for example, heavier at the start then lighter as the athlete speeds up). They also collect data, which is valuable for monitoring progress.
Cons: Extremely expensive and generally only available in elite training centres. Even within the Australian Sport Institutes, their availability is extremely limited.
Combining Resistance Tools
In some cases, coaches get creative – for instance, having athletes sprint while pushing a sled or a weighted sled with wheels (prowler) for short distances, or uphill starts in sand. While these fall more into strength drills than pure sprinting, they are variations that serve a similar purpose (developing the drive phase). Partner pushes (one athlete pushes against another’s back at the start) or towing a tire instead of a sled are other improvised methods. The pros and cons largely mimic those of sleds and hills.
Key Takeaway for Coaches: Each tool can be effective if used in accordance with its strengths. Sleds and hills have evidence that they are particularly suited for improving the drive phase and horizontal force (with strong evidence backing them), whereas parachutes and very light sleds are sometimes used to subtly tax the later phase of a sprint. Coaches should choose the tool that fits the training environment and the athlete’s needs. For example, a grassroots club with no sled might do hill sprints and band-resisted runs, which can still yield excellent acceleration gains. An elite group with access to weight sleds will likely use them because of the fine control over loading. It’s also perfectly reasonable to rotate tools to keep training fresh – e.g. hills in one training cycle, sleds in the next.
The common principle is that all these tools create an overload that the athlete must overcome, thereby stimulating greater force or power output than unresisted sprinting alone.
Resisted vs. Unresisted Sprinting: Effects and Comparisons
A central question for coaches is how resisted sprint training compares to traditional free sprint training. Should resisted runs replace some free sprints, or just complement them? Key insights from Aldrich et al. (2024), which conducted a meta-analysis of all research into the effect of resisted sprint training highlighted the following considerations:
Acceleration Gains vs. Max Velocity Gains: It’s well established that resisted sprinting can improve acceleration ability – athletes become quicker over the first steps. Resisted training tends to increase the athlete’s horizontal force production and the rate of force development. This often manifests as faster 5 m or 10 m split times after a training block with sleds or hills. Improvements in maximum velocity are less direct. Free sprinting at or near top speed is usually needed to improve that phase. Light resisted work can assist max velocity slightly (by forcing high turnover against a small load), but if the resistance is too high, the athlete never truly reaches top speed in training. In one comparative study, both heavy and light resisted groups improved 30 m sprint performance similarly, but only the lighter load group had a notable edge in flying sprint speed. This suggests unresisted sprinting remains irreplaceable for developing top-end speed, whereas resisted sprints are mainly a tool to enhance the power needed for take-off and early phase.
Resisted Training vs. Just Sprint Training: Does adding resistance yield greater benefits than sprinting without resistance? The evidence here is mixed. A recent meta-analysis of 15 studies (2005–2022) found that resisted sprint (RS) training did not produce significantly greater improvement in sprint performance than unresisted sprint training on average. In other words, athletes got faster over 5–30 m with both methods, and RS was only marginally (and not statistically significantly) more effective. Most studies show both groups (resisted and normal sprints) improve, which means simply sprinting fast regularly is a potent training stimulus by itself. However, it’s important to interpret this carefully. The fact that RS training isn’t vastly superior doesn’t mean it has no value – rather, it indicates that resisted sprints are a comparable alternative or supplement to regular sprints, not a magic bullet. In practice, coaches often combine them: for example, doing a sled sprint followed by a free sprint (contrast method) to get the best of both worlds. The meta-analysis also noted a wide range of loads and protocols used across studies, which could dilute clear effects – some studies used very light loads, others heavy; some trained 4 weeks, others 10 weeks. It’s possible that carefully targeted use of resistance (e.g. heavier loads for those lacking acceleration strength) might outperform generic training, even if overall averages show parity.
Mechanics and Kinematics: Resisted sprints do change sprint kinematics acutely – usually a lower stride frequency and longer ground contact as the athlete pushes harder. The question is whether this carries over positively or negatively to unresisted sprinting. Coaches once feared that spending too long with heavy sleds might engrain a “slow” stride pattern. But as mentioned, studies have not found subsequent slowing of sprint times; on the contrary, sled-trained athletes often improved their unresisted times. The logic is similar to weight training: performing heavy squats doesn’t make you slower in a jump, it actually helps when you remove the weight. The key is to always reintegrate technique – runners should frequently sprint without resistance (in the same session or training week) to practice moving fast. Many experts stress that resisted sprints are a means to an end, not an end in themselves. They build underlying qualities (like horizontal force) that must then be converted into better free running. In fact, resisted sprint performance itself will improve more than free sprint performance – athletes get better at towing the sled disproportionately. Whether that extra resisted capacity transfers fully to normal sprinting over time is still being studied. So, coaches should ensure that athletes don’t become “champion sled-pullers” who then fail to capitalise on it in normal sprints. The antidote is simply to keep regular sprinting in the program alongside resistance.
Complementary Training Effects: A sensible viewpoint is that resisted and unresisted sprints offer complementary benefits. Resisted sprints can overload the force aspect of the force-velocity spectrum, while unresisted (or assisted) sprints train the velocity aspect. For complete speed development, athletes likely need exposure to both high force (low velocity) and high velocity (low resistance) stimuli. For example, heavy sled pulls might increase an athlete’s peak propulsive force, enabling a more explosive start, whereas flying sprints at 100% intensity train the nervous system to fire rapidly and coordinate movements at extreme speeds. Many coaches plan training to address the entire spectrum: heavy resisted work, light resisted, free sprints, and even assisted/overspeed, to ensure no gaps. If an athlete only ever did heavy sleds, they’d get strong but might struggle when the sled is removed; conversely, if they only ever did unresisted sprints, they might plateau if their acceleration is limited by strength. By blending methods, athletes often see the best overall gains. Some anecdotal practices: doing a heavy sled drag followed by a block start without sled can produce a potentiation effect – the unresisted sprint feels “lighter” and the athlete may run faster immediately after the resisted effort. While evidence for a long-term potentiation is mixed, in the short term this contrast can be a useful training trick or confidence booster.
Injury and Fatigue Considerations: Resisted sprints can be demanding on the muscles (especially glutes, hamstrings, calves). However, because the speeds are lower, some coaches find sled sprints safer or less stressful on hamstrings than full-speed sprinting, which can cause pulls if not careful. For athletes returning from injury, a bit of resistance might actually slow them enough to reduce re-injury risk while still allowing high effort. On the other hand, excessive resistance or uphill running can stress the Achilles and calf due to longer push-off times. As always, introduce new methods gradually and watch the athlete’s response. Unresisted sprints at maximum velocity have a higher risk of hamstring strains due to the extreme speed and stretch; resisted sprints mitigate that by capping velocity. So, in a rehab setting or early pre-season, coaches sometimes use resisted runs as a bridge to full-speed work.
Psychological and Technical Benefits: Athletes often report that heavy resisted sprints teach them the feeling of driving hard. It can reinforce cues like “push the ground away” or “explode out” because the feedback of the resistance makes it obvious if they are producing force. Then they carry that aggression into normal sprints. Conversely, unresisted sprints teach relaxation and turnover at speed. Therefore, mixing the two can also help an athlete find the right blend of power and fluidity. If a sprinter tends to be over-cautious or lacks aggression in acceleration, a period of dragging a heavy sled might unleash more intensity in their start. If another sprinter is powerful but tight at top speed, doing more flying sprints (no resistance) at race pace will teach them to be efficient.
Key Takeaway for Coaches: Resisted sprints are not a replacement for free sprints but a valuable supplement. They specifically target the force-generation capacity and can yield comparable overall gains to normal sprint training when used appropriately. The best results appear to come when coaches intelligently combine methods – using resistance to address specific needs (like improving first-step quickness), and always following up with unresisted practice to apply those gains to real sprintings. Given that literature is equivocal on whether sprinting with resistance is superior to just sprinting, a pragmatic approach is to use resisted runs to “tune” an athlete’s sprint profile (e.g. if they have a weakness in acceleration) but continue to emphasise actual sprinting for ultimate performance. As one review concluded, “resisted training improves the performance in resisted conditions more than normal conditions, so it’s ultimately the blend of training that makes the athlete faster in competition”.
Resisted sprints can be an effective addition to a coach’s toolkit for developing acceleration and speed. By following the best practices outlined – optimal loading strategies, appropriate distances, sensible volumes, proper periodisation, and the right choice of tools – coaches can safely and effectively harness resisted sprint training. Whether it’s a young athlete learning to push out of the blocks with a light sled, or an elite sprinter towing a heavy sled in winter to find an extra edge, the principles remain the same. Used wisely, resisted sprints help athletes generate greater force in less time, which ultimately is the foundation of running fast. As with any training method, continual assessment and adjustment will guide the coach to the optimal mix for their athlete.
