Using anaerobic speed reserve to profile players and individualize training

The anaerobic speed reserve (ASR) is an increasingly popular tool for optimizing training and performance across various sports. It not only allows practitioners to individualize training prescription but also enables a tailored approach to recovery within and between sessions.

ASR is the difference between an athlete’s maximal sprinting speed (MSS) and maximal aerobic speed (MAS). This provides a clear picture of the athlete’s “reserve” capacity, and is a way to profile or categorize athletes. ASR distinguishes between athletes who have similar aerobic capacities but display different performance characteristics. But the magnitude, or numerical value, of the ASR is just one of several useful attributes of the relationship between an athlete’s MSS and MAS.

Consider two athletes who have the same maximal aerobic speed but different maximal sprinting speeds. They will obviously have different ASRs. But more importantly for programming conditioning sessions, the proportion of ASR each athlete uses will be different. This relationship become more significant than just the value of the ASR or the percentage of MAS they are working at.

For example, two athletes have a MAS of 4.5 m/s, but athlete A has an MSS of 10 m/s (ASR = 5.5 m/s) and athlete B has an MSS of 8 m/s (ASR = 3.5 m/s). Prescribing a conditioning session based solely on their MAS may under work one athlete and over work the other: if both athletes were prescribed a conditioning session at 120% of their MAS (5.4 m/s), then athlete B would be working at 26% of their ASR while athlete A would only be using 16%. This would lead to significantly different physiological responses, highlighting the importance of using ASR to ensure uniform physiological stress and subsequent adaptation across a group of athletes ^[1].

Profiling athletes on the MSS – MAS relationship

The ratio of MSS to MAS offers a clearer understanding of how an athlete may tolerate and adapt to training loads, and provides insight into an athlete’s muscle fibre typology, allowing practitioners to tailor conditioning programs even further.

The ratio of MSS to MAS helps differentiate between three locomotor profiles: speed, hybrid, and endurance. While these ratios have not been scientifically validated across all sports, they serve as useful benchmarks for sports such as football:

•           Speed: >1.90

•           Hybrid: 1.80 – 1.90

•           Endurance: <1.70 ^[2,3]

We can make certain assumptions about how an athlete might handle a particular training load based on the size of the reserve. For example, a “speed” profile athlete with a large reserve has more capacity to work within, while an “endurance” profile athlete with a much smaller reserve has less of a buffer. Table 2 shows the relative effort an athlete of each profile would exert when working at the same percentage of their ASR. This illustrates that for an athlete with a smaller reserve there is not a significant speed difference between working at 40% vs. 50% of their reserve, although the relative energy cost would be the same for each.

The size of the reserve alone does not paint the full picture. It does not account for primary values like an athlete’s MAS, which plays a critical role in determining overall tolerance to high intensity training.

Consider two athletes with an MSS of 9 m/s. Athlete A has an MAS of 5 m/s, while Athlete B’s MAS is 4 m/s, resulting in anaerobic speed reserves of 4 m/s and 5 m/s, respectively. While it might seem like Athlete B has a larger reserve and potentially better capacity, B’s slower MAS suggests a lower tolerance to overall load. In contrast, athletes with higher MAS typically cope better with load.

The capacity component is often overlooked when profiling athletes, particularly those with speed profiles.

While these athletes are rightly recognized for their ability to operate at higher percentages of their ASR, it’s essential to consider two critical points.

First, speed profile athletes must prioritise quality in their training, which makes adequate rest both within and between intense sessions a key consideration. Second, their MAS provides valuable insight into their capacity to tolerate intense exercise. This makes MAS a particularly effective screening tool, especially when returning to training following an off season. The graph below illustrates two speed profile athletes, highlighting how athletes with the same profile can exhibit vastly different levels of load tolerance. This underscores the importance of not focusing solely on the size of the reserve or the MSS:MAS ratio. Instead, understanding MAS and MSS in context is crucial for designing accurate, individualized approaches to high intensity training. By doing so, practitioners can better manage the balance between performance gains and recovery needs for these athletes.

Programming based on MSS and MAS profiles

In team sports like soccer, specific profiles often align with particular positional demands.  

For example, wingbacks typically display hybrid profiles due to their requirement to perform repeated high intensity sprints over extended periods, often exceeding 60 minutes. These players must balance high output with minimal recovery between efforts. In contrast, endurance profiles are common amongst midfielders or centre backs, where the ability to sustain high volumes of work with relatively lower intensity outputs is crucial. Finally, speed profiles are most often associated with strikers, for whom explosive sprinting efforts are vital. The long rest intervals between these high intensity actions make these positions well suited to the physiological strengths of speed profile athletes. 

Conditioning for “speed” profile athletes

A speed profile athlete, with a relative ratio (MSS/MAS) of >1.9, is assumed to be Type IIx muscle fibre dominant. These athletes excel at producing high outputs over short durations, but require extended recovery between efforts. In field sports, these athletes rely on their speed to outpace defenders when needed. However, the trade off is that they need longer recovery periods to be ready for subsequent efforts.

For these athletes, alongside the demands of their position, the physiological focus for conditioning should be on enhancing their capacity for repeated sprints.

Although it might seem intuitive for speed profile athletes to focus on aerobic work to increase their MAS and overall capacity, they tend to benefit more from training that aligns with their strengths. Even at low intensities, these athletes, especially when glycogen depleted (e.g., under-recovered or during a second training session of the day), may rely more heavily on fast twitch muscle. This can lead to an increased VO2 slow component, making it difficult for them to maintain a steady state during continuous low intensity exercise  ^[1,4].

By focusing on repeated sprint work, they can enhance their capacity through various mechanisms, including improvements in aerobic function at the muscular level.

As a result, time spent at VO2max becomes less critical, and prioritizing what the athlete tolerates well is key.

That said, the neuromuscular load associated with repeated sprint work can lead to unwanted fatigue, particularly in athletes with a low training age. This can potentially affect subsequent training sessions.

As always, context is crucial. In addition to individualizing around each athlete’s specific needs, preferences, and risk factors, practitioners must also strategically align conditioning with the physical, technical, and tactical demands of the program and the phase of the season.

These athletes often perform best with a “day on, day off” approach, allowing them to train intensely on their training days and maximize recovery on their off days. However, since we don’t always have full control over the training schedule, managing these athletes across back to back training days is crucial for their long term adaptation.

They also may struggle with double session days, with a field session in the afternoon and in the morning. In those cases, I prefer to prioritize one session for intensity and use the other for skill and execution work. Again, this is not always in our control, so focusing on recovery strategies and nutritional replenishment between sessions becomes vital in managing their training response.

Conditioning for hybrid athletes

Hybrid athletes can tolerate and benefit from a range of conditioning across the intensity spectrum. They have high outputs and high capacities, and are able to keep going with minimal rest between efforts. These are often your wingers and outside backs, regularly and frequently producing high intensity outputs.

These athletes have a high tolerance for both intensity and volume, but there is a tipping point.

The focus should be on balancing aerobic and anaerobic work, ensuring one ability is not developed at the expense of the other; and understanding the athlete’s unique profile, including any underdeveloped areas (anaerobic or neuromuscular), in order to take their individual context into account.

Monitoring them with regular screening and fatigue assessments is key to identifying early signs of fatigue and reducing injury risk. Hybrid athletes often seem capable of handling substantial workloads, consistently backing up big weeks of training without showing obvious signs of fatigue— until an unexpected injury occurs. Proactive rests — before any signs of fatigue appear — can mitigate this risk. This can be a difficult “sell” to a coach who sees the athlete performing well without noticeable signs of fatigue. To make your case, it’s helpful to highlight leading indicators of fatigue, such as skill breakdowns during training ^[5]. Objective measures like the reactive strength index, gathered from force plates, can also offer valuable insights into an athlete’s neuromuscular fatigue and help reinforce the need for rest.

Conditioning for “endurance” profile athletes

The final profile type is the endurance profile: athletes who excel at handling high volumes but struggle to achieve or sustain high intensities. These are typically your midfielders, accumulating significant total distance during a match but contributing less in terms of high speed distance.

Endurance profile athletes tend to tolerate and thrive on high volumes, especially at lower speeds. They often handle double session days and back to back high volume training sessions well.

For these athletes, sub-max endurance work and longer durations using small proportions of their ASR are effective for building their physiological capacity.

While they can manage high volumes, these athletes are prone to fatigue if the intensity and time at intensity get too high. Their reliance on aerobic metabolism to meet energy demands means excessive intensity can lead to unwanted fatigue. Often, these athletes need just a touch of intensity, as energy is not typically their limiting factor.

If the goal is to increase their MSS (and, by extension, their anaerobic speed reserve), neuromuscular and muscular work may be more beneficial. For example, improving lower body strength, refining running mechanics, and incorporating regular low amplitude plyometrics can offer a better stimulus with a lower physiological cost than intense conditioning.

These athletes often struggle with two or more consecutive days off (e.g., a bye week). While it’s difficult to manage during these periods, where possible, avoiding two full days off may be more beneficial for the endurance athlete. When given training loads at a manageable intensity, they typically require minimal rest between sessions and can maintain their performance across multiple efforts and days of training.

It’s important to note that prescribing conditioning protocols from the ASR should only be used when the desired intensity is greater than 100% of the MAS. Therefore, this example does not describe conditioning drills below this intensity.

Off-feet conditioning

The concept of ASR prescription is also useful for off-feet conditioning sessions.

Similar to on-field conditioning, the ASR driven approach to profiling and prescription helps minimize the risk of maladaptive responses or non-responses to training, ensuring consistent physiological stress across a group of athletes. While the timing, intensity, and conditioning protocol might remain similar to on field sessions, the prescribed distances or power outputs will need to be adjusted based on measurements taken from the ergometer (erg).

This approach to off-feet conditioning is particularly useful in athletes who are rehabbing from injury. Although the peripheral adaptations that off-feet conditioning induces are not specific to football players, athletes can still attain beneficial physiological adaptations from these sessions.

For example, the athlete could complete a 5–6 minute all out effort and record the average speed (m/s) or power output (distance/time, or the erg’s displayed power) over that period.

To assess MSS or peak power, add a 10 second maximal effort test, typically on a different day. Record the peak speed or power from a three second window within that 10 second block. Since this is not always feasible on standard ergs, I usually take the peak from the overall 10 second effort.

From there, the programming follows the same principles as an on-field session, using profile specific proportions of the anaerobic speed reserve, with appropriate work to rest ratios and recovery strategies between sessions. Table 7 shows an off-feet conditioning protocol that a speed profile athlete could complete when they are unable to perform on field conditioning.