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Coaching Athletes: Endurance Training Part 1

Training to Raise the Ceiling; Limitations on Endurance

By: Nick Soleyn, Editor in Chief, PBC

Read Part Two

The strength and conditioning coach’s domain is the gym—a controlled environment dedicated to physical improvements by means of predictable adaptations to different kinds of work. Of course, the work sometimes extends out of doors and to other venues, but these are still the gym. No one is keeping score. There is no winning or losing. There is just the work. For athletes, the gym encompasses the distinctive effort to improve physical fitness for life and sports. Understanding the difference between this physical training and practicing and playing sports is crucial to developing athletes.

I like to think of the gym as the place where we raise athletes’ ceilings. No matter how good a person is at a sport, an athlete can never exceed his or her potential, and it is physical limitations that most often make up that ceiling on performance. Sometimes, the potential for certain things is fixed; genetics and anthropometry play a significant role in competitive sports. There are, however, a lot of things we can influence through training, especially for under-developed athletes.

The strength and conditioning coach wants to improve the athlete’s capacity to work, move, practice, and perform. We do this by targeting adaptations—intentional physical changes that include a multiplicity of known responses to things people can do with their bodies. For simplicity’s sake (and marketing purposes), we tend to lump these adaptations into the broad categories of “strength” and “conditioning,” but an athlete’s goals (and the ways to reach them) are more individualized and subtle.

A good strength and conditioning coach guides the athlete to develop the right kinds of strength and the right kinds of conditioning for the athlete’s goals. Unfortunately, many strength and conditioning coaches attempt to signal their competence to do this with a large and varied bag of tricks, using all types of specialized training equipment, devices, and setups. Usually, they claim that these exercises are more functional and specific to the athlete’s needs.

Realistically, the types of adaptations that we can improve in the gym are not that varied. Above, I mentioned that adaptations are nuanced, and they are. Strength depends not just on the development of muscle hypertrophy, for example, but on the athlete’s readiness to exert force, skilled movement, neuromuscular changes, and some ability to fuel all the physical activities that make up their sport. And all of this changes with the athlete’s training history and current work capacity. But we do not need hundreds of exercises, workouts, training cycles, or devices to improve all those things. Rather than a large bag of tricks, all you need is a handful of highly effective exercises, the proper tools, and some understanding—giving you good timing and the ability to prioritize and structure training for different goals.

The focus of this article is on endurance training for athletes through conditioning work in the gym. I’ve written about conditioning and energy systems training for general health here. For this article, we will focus on different aspects of endurance, including VO2 max and lactate threshold training.

Training to Raise the Ceiling: Endurance Limitations on Performance

Athletes want to show up for games and practice with their greatest possible potential. If they are less strong, less well conditioned, less flexible, or less fit for their sport, compared to what is reasonable at that point in their athletic development, then they are showing up with trainable limitations. Similarly, if they are overly focused on training things they are already good at when they could improve rate-limiting weaknesses (weaknesses that limit performance despite improvement in other areas), then they are using their gym time inefficiently.

No athlete is perfect, and most young athletes are underdeveloped. So, the strength and conditioning coach should always be able to prioritize training goals and organize the athlete’s gym time in a most-bang-for-your-buck kind of way—targeting the biggest, most useful adaptations first and building a solid foundation for other, narrower improvements that will come later.

In the case of athletes, how much bang one gets is how much their general physical capacity will improve their sports performance. This will differ from sport to sport and athlete to athlete.

“In some sports disciplines, such as 100-m run, marathon, and rowing, performance is closely related to the physical capacity of the athletes, whereas in other sports like ball games, high technical and tactical standards may compensate for weakness within the fitness level.” (Bangsbo 2015)

Where the sport requires less technical movements, where play less reactive or dynamic, the result is—more or less—equivalent to the performance (e.g., time in a race, total in powerlifting, distance in a long jump or throw). Skill is often less varied at higher levels of competition in these sports. Instead, physical capability, game-day preparation, and execution are much bigger determinants of performance.

Sports that require reactive play, specialized skills, and constantly changing efforts may rely less on raw physical abilities like strength, endurance, and explosiveness, but these attributes still make up the foundation of athletic performance. They just become less disparate among high-level competitors. So, for all kinds of novice athletes, the strength and conditioning coach must know how to build these foundational attributes.

As an example, we build strength by focusing on two primary aspects—building muscle and creating readiness for voluntary muscle activation. We keep track of each of these by monitoring athletes’ performance on certain benchmark lifts (most commonly the squat, bench, deadlift, and press). For a powerlifter, whose sport directly reflects performance on three of these lifts, gym time will revolve around building strength with minimal conditioning work beyond what’s necessary to improve the athlete’s capacity for training or shore up general fitness concerns.

The focus of this article, however, is building endurance. We can simplify this task by recalling that our goal is to move the athlete’s ceiling, focusing mostly on their physical potential. Just as with strength training, the first step is identifying the primary trainable factors that will help improve our athlete’s potential. We can identify these factors by looking at the things that limit a person’s endurance. Then we can structure training to push those limitations upward.

Limitations on Endurance

VO2 max (maximal oxygen consumption), lactate threshold, and efficiency or economy of movement are the main trainable factors that limit endurance for most sports.

“Generally, endurance performance is determined by maximum oxygen uptake (VO2 max), work economy (mechanical efficiency), and the relative intensity (fractional utilization of VO2 max) that can be sustained throughout the exercise.” (Bangsbo 2015)

Why are these such powerful limitations? Work requires energy. Energy for muscles comes from ATP, which can be created through oxidative and non-oxidative means. While individual, short-burst efforts might rely primarily on stored ATP, full performances in sports are rarely one-and-done. Even a powerlifting meet involves a full day punctuated by nine all-out efforts. The longer the duration and the more sustained the activity, the more muscles rely on oxidative means to replenish ATP (Bassett 2000). VO2 max tells us the maximum amount of oxygen a person can pull from their environment and send to their muscles, making it an important limiter of sports endurance.

Lactate threshold is the intensity at which lactate begins to accumulate in the blood at a faster rate than it can be cleared. Increased concentration of lactate in the blood is correlated with fatigue, but the exact cause of fatigue is unclear. It’s possible that the drop in blood pH levels from accumulating lactate causes fatigue. Lactate accumulation may interfere with the regulation of calcium ions in the muscle cells, which are important for muscle contraction. OR the accumulation of lactate in the blood may activate pain receptors and lead to central fatigue. In any case, lactate itself is not bad. It is a valuable energy source during exercise. The important aspect of a person’s lactate threshold is how well it predicts fatigue and how trainable that connection seems to be:

“In untrained subjects, the upturn in lactic acid concentrations is seen at about 60% of VO2 max. Trained subjects can usually exercise at 75%–85% of Vo2 max before there is a marked increase in blood lactate concentration.”

For longer endurance events, one of the better predictors of an athlete’s performance is his or her speed at lactate threshold. This measure encompasses the three above factors, providing a snapshot of the athlete’s overall endurance. For example,

“the word class runner Paula Radcliffe . . . had an improvement in 3000-m performance by 8% from 1991 to 1993 despite a fall in VO2 max from 73 to 66 mL/kg/ min. In the same period, she improved her running economy from 53 to 48 mL/kg/min at 16.0 km/h leading to an increase in the running speed at VO2 max from 19.0 km/h in 1991 to 20.4 km/h in 1995 (Jones, 1998).” (Bangsbo 2015)

VO2 max and Lactate Threshold are complex and overlapping systems. Increasing one’s oxidative capacity should also increase their lactate threshold, but there does seem to be some benefit to direct “lactate threshold training,” which may have as much to do with practicing hard, sustained efforts as it does with the physiological determinants of endurance.

Changes in VO2 max, lactate threshold, and efficiency do not have a one-to-one impact on endurance. Also, there are other factors that will affect an athlete’s endurance on any given day: recovery, sleep, nutrition, hydration, pacing, strategy, etc. We cannot expect that our athletes will see immediate improvements in their sports performances simply because we added sled pushes or hill sprints to their training. In improving athletes’ capacity for endurance, we should expect them to better handle higher workloads, but whether that change leads to better in-game performances is not up to us.

Also, one of these big components of endurance is not directly under the strength and conditioning coach’s influence: efficiency or economy of movement. Efficiency is part skill, part muscular endurance, part mental toughness, and is influenced by practice, experience, and anthropometry. Since this article focuses on conditioning work to improve endurance, it does not cover efficiency or economy of movement. Athletes may improve these things as a side effect of conditioning training, but sport-specific efficiency is not the goal.

Focusing on maximal oxygen uptake (VO2 max) and lactate threshold makes our training goals clearer: identify the athlete’s needs and design a training program that will improve and maintain their capacity for endurance in a way that fits with the athlete’s other responsibilities. I cover the balancing act that strength and conditioning coaches face when training athletes here. The current article will focus more on the work of improving these two factors.

In the next installment, I will discuss VO2 max and lactate threshold improvements, what goes into them, and what research says about how to improve them.


Bangsbo, J. 2015. “Performance in Sports – With Specific Emphasis on the Effect of Intensified Training.” Scandinavian Journal of Medicine & Science in Sports 25 (December): 88–99.

Bassett, David R. 2000. “Limiting Factors for Maximum Oxygen Uptake and Determinants of Endurance Performance:” Medicine & Science in Sports & Exercise, January, 70.

Esfarjani, Fahimeh, and Paul B. Laursen. 2007. “Manipulating High-Intensity Interval Training: Effects on , the Lactate Threshold and 3000m Running Performance in Moderately Trained Males.” Journal of Science and Medicine in Sport 10 (1): 27–35.

Joyner, Michael J., and Edward F. Coyle. 2008. “Endurance Exercise Performance: The Physiology of Champions: Factors That Make Champions.” The Journal of Physiology 586 (1): 35–44.

Oliveira-Nunes, Silas Gabriel de, Alex Castro, Amanda Veiga Sardeli, Claudia Regina Cavaglieri, and Mara Patricia Traina Chacon-Mikahil. 2021. “HIIT vs. SIT: What Is the Better to Improve VO2max? A Systematic Review and Meta-Analysis.” International Journal of Environmental Research and Public Health 18 (24): 13120.

Ozaki, Hayao, Jeremy P. Loenneke, Robert S. Thiebaud, and Takashi Abe. 2013. “Resistance Training Induced Increase in VO2max in Young and Older Subjects.” European Review of Aging and Physical Activity 10 (2): 107–16.




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