Anaerobic Speed Reserve: How to Calculate and Use It

Two wide receivers post the same maximal aerobic speed on a 30-15 test, 16.5 km/h, and their strength coach assumes their conditioning prescriptions can be identical. Six weeks in, one of them is stalling on every fly-in sprint drill while the other is cruising through repeated 30-meter efforts with a full second to spare on his personal best. Same aerobic engine, wildly different outcomes, and MAS alone never explained why.

The missing number is anaerobic speed reserve, the gap between an athlete's maximal aerobic speed and their absolute top sprint speed. One receiver has a huge reserve, a genuine top-end sprinter sitting on top of an average aerobic base. The other has almost none, an aerobically dominant runner whose top speed barely clears his aerobic ceiling. Prescribe the same speed-endurance session to both and you overload the small-reserve athlete's only real strength while barely touching the big-reserve athlete's actual limiter.

This guide walks through how to calculate anaerobic speed reserve from two numbers most programs already collect, what the sport-science literature says it does and does not predict, a field protocol for getting both inputs right, and how to turn the resulting number into a training-zone decision rather than a stat that sits in a spreadsheet nobody opens again.

Anaerobic speed reserve (ASR) is defined simply as maximal sprint speed (MSS) minus maximal aerobic speed (MAS), both expressed in the same unit, usually km/h or m/s. The concept was formalized by Sandford, Laursen, and Buchheit (2021) in Sports Medicine as a framework for individualizing high-intensity interval prescription, building on Gerald Blaauw's original repeated-sprint-ability work and Buchheit's earlier applications in team-sport conditioning.

MAS is the velocity at which an athlete reaches VO2max, typically estimated from a field test such as the 30-15 Intermittent Fitness Test or a standard 1200m time trial, then converted to km/h. MSS is the athlete's fastest sustained velocity over a short window, almost always taken from a 30-40m timed sprint using the peak instantaneous split rather than the average speed across the whole distance, since average speed over a short sprint always understates true peak velocity.

Worked example: an athlete runs a 30-15 IFT to a final stage of VIFT 19.5 km/h, which converts to an estimated MAS of roughly 16.6 km/h using the standard 30-15 correction factor. The same athlete clocks a peak instantaneous speed of 31.2 km/h on a radar-timed flying 20m sprint. ASR is 31.2 minus 16.6, which comes out to 14.6 km/h. A teammate with an identical MAS of 16.6 km/h but a peak speed of only 27.0 km/h has an ASR of just 10.4 km/h, over four km/h less reserve despite an identical aerobic number. That four km/h gap is the entire reason the two athletes in the opening example responded so differently to the same conditioning block.

Sandford, Pearson, Allen, Malcata, Kilding, Ross, and Laursen (2019) tested elite middle-distance runners and found that athletes with a larger ASR relative to their MAS reached VO2max faster and tolerated a higher proportion of severe-intensity work during interval sessions than athletes with a smaller reserve at the same relative aerobic intensity. The practical takeaway was that prescribing intervals purely as a percentage of MAS, without accounting for ASR, systematically under-loads big-reserve athletes and over-loads small-reserve ones on the same nominal session. The study's limitation is its sample: a small, homogeneous group of national-level middle-distance runners, so the exact interval durations they recommend do not transfer directly to team-sport athletes without adjustment.

In team sports specifically, Buchheit (2019) and related work from his applied research program showed that ASR correlates meaningfully with an athlete's tolerance for repeated-sprint work, and that two players matched on MAS but differing on ASR need different repeated-sprint-ability (RSA) prescriptions to reach the same relative training stress. A large ASR athlete generally needs longer recovery and can tolerate faster absolute sprint speeds in an RSA set, while a small ASR athlete fatigues at a lower absolute speed but often recovers faster between reps because a larger share of the effort sits closer to their aerobic ceiling. The caveat here is that most of this applied work comes from soccer and rugby cohorts and has not been independently replicated across a wide range of other field sports at the same depth.

Neither line of research claims ASR is the only variable that matters. It is one lens on top of existing force-velocity and repeated-sprint testing, not a replacement for either, and it says nothing directly about change-of-direction ability or deceleration capacity, which are separate qualities entirely.

Test MSS before MAS in the same session if you are running both on the same day, and ideally on a separate day from any conditioning test entirely, since residual fatigue from an aerobic test will depress a subsequent sprint result and inflate the calculated reserve artificially. Use a flying sprint setup: a 10-15m rolling start into a 20-30m timed zone, so the athlete is already at or near top speed when timing begins, rather than a standing start that captures acceleration mechanics instead of peak velocity.

Run 2-3 trials with full recovery, at least 3-5 minutes between efforts, and record the single fastest instantaneous split rather than an average across trials. For MAS, the 30-15 Intermittent Fitness Test is the more practical field option for team-sport athletes because it includes direction changes and matches the intermittent demand profile of most invasion sports, while a straight 1200m time trial suits endurance-background athletes better. Whichever test you choose, keep it consistent across retests, since converting between different MAS-estimation methods introduces error that can shift the calculated ASR by a full km/h or more.

Re-test both ends of the equation together every 6-8 weeks. Testing only MSS or only MAS in isolation and assuming the other number held steady is a common shortcut that quietly corrupts the ASR figure, because a training block aimed heavily at one quality almost always shifts the other by a small but real margin.

PoinT GO tracks peak instantaneous sprint velocity and interval pacing data on the same device, giving coaches both halves of the ASR calculation without juggling separate testing equipment.

Once an athlete's ASR is calculated, use it to bias, not replace, the rest of the program. A small-ASR athlete, one whose top speed sits close to their aerobic ceiling, gets the most out of true maximal-velocity exposures: 10-20m flying sprints at 95-100% effort with full recovery, two to three times per week, layered onto whatever aerobic and repeated-sprint work the sport already demands. Chasing more aerobic conditioning with this athlete wastes training time on a quality that is already their strength.

A large-ASR athlete, the genuine speed outlier sitting on a modest aerobic base, needs the opposite bias: extensive tempo runs at 70-80% of MAS, longer repeated-sprint sets with shorter recovery ratios, and interval work that pushes their aerobic ceiling upward, since their top speed is rarely the constraint in a match. This is also the athlete most likely to look explosive in isolated sprint testing but fade specifically in the third quarter of a match, a pattern that a raw sprint time alone never explains but an ASR calculation usually does.

ASR works best paired with the acceleration and force-velocity data covered in our force-velocity profile individualization guide, since a large reserve built on poor acceleration mechanics still shows up as a slow player over the first 10 meters even though the raw top-speed number looks excellent. Retest at block transitions, and treat a shrinking ASR after a heavy aerobic block, or a growing one after a heavy speed block, as confirmation the program is doing what it was designed to do rather than a surprise.

PoinT GO's sprint tracking pairs peak instantaneous velocity with acceleration splits and repeated-sprint fatigue data covered elsewhere in this guide series, giving a coach the full speed profile behind a single ASR number. Visit PoinT GO Research for validation data and setup guides.