TYPES OF TRAINING RUNS
We all have a reason to run. Perhaps we are fueled by icons of the sport, feeding off inspiring performances from the Paris Olympics. Or maybe we’re inspired by the stress, anxiety, and tension we feel that prompts us to get out the door and clear our head. Sometimes we are running for the sake of pushing ourselves, expanding the realm of what is possible for us. Other times we are running as a choice to be a better person today than we were yesterday, deciding to become a healthier and stronger version of ourselves. Every run has a purpose, and the purpose of every run changes from day to day.
“Every run has a purpose” - Coach Chris Bennett
Take some time to reflect pre-run. It is important to know your “why”. Why are you running today? Is the purpose of this run to build your aerobic base, improve your speed, or simply to clear your head? When you lace up your shoes and step outside, understand the purpose of the run you are about to complete. This is especially important when training for a race with a goal in mind. We must be deliberate as athletes. The goal of any well-designed training plan is to develop specific realms of fitness to meet the demands of your goal race. Let’s look at the various types of runs within a training plan so we can understand the purpose of each run.
Easy/Aerobic Runs
The vast majority of running should be done at an easy effort. This is commonly done at a “conversational” pace where you can chat with a friend, speaking in full sentences out loud. You might hear this type of training referred to as “zone 2”, at about 60-70% of your max heart rate. Breathing is not significantly labored at this pace, inhaling for 3-4 steps and exhaling for 3-4 steps.
Physiologically this training intensity improves your cardiovascular endurance and efficiency. Easy running strengthens your heart muscle. As you run harder and faster, your cardiac output (CO) has to increase to continue supplying the skeletal muscle with oxygen and fuel. CO is the product of heart rate (HR) and stroke volume (SV).
CO = HR x SV
As intensity of running increases, heart rate and stroke volume increase as well. However, stroke volume plateaus at about 60% of your max; even if you continue pushing the pace, the heart is beating as forcefully as it ever will. Therefore the heart muscle strengthens tremendously, even at these easy efforts.
In the periphery, we see tremendous benefits in the muscle itself from easy aerobic running. The muscle fiber contains numerous mitochondria, which receives nutrients from the bloodstream and works to turn fuel into energy. In response to training at this intensity, the mitochondria increase in size and number. The mitochondria even moves toward the periphery of the muscle cell to be closer to the capillaries and oxygen supply, all working to improve efficiency. These adaptations happen as a function of time spent running, not speed. And if you’re able to maintain an easy effort for these training runs, you will be able to sustain that effort for a longer time. Keep your easy days easy.
Marathon Pace
Marathon pace runs are specific for marathon training, but can also be done if training for the half marathon or 10k distances. This can also be referred to as “steady” or “tempo” runs, slightly slower than lactate threshold efforts detailed below. These runs require slightly more effort than a general aerobic run, but is still an aerobic effort. If you are training with heart rate, this should be in zone 3 or about 70-80% of max heart rate. This intensity is also referred to as LT1, lactate threshold 1, or ventilatory threshold 1, as blood lactate levels increase above baseline but remain at a steady-state concentration. At this training intensity, the body shifts its primary energy substrate from fatty acids to carbohydrates and glycogen as the skeletal muscle demands more fuel.
Consider a marathon pace effort to be a comfortable effort that can be held for 2+ hours, but it requires significantly more focus and attention than an easier zone 2 run. You should be able to speak in sentences, but not paragraphs. Marathon pace is a powerful component of any marathon training program, especially when implemented in the middle of a long-run as it trains the body and the mind to sustain this pace over long durations.
Threshold
To understand threshold training, we have to be aware of lactic acid. Lactate is produced even at rest as a normal byproduct of metabolism, and it is constantly circulating in the blood. As lactate is produced, it is cleared as the blood transports lactate to the liver and the liver turns it back into glucose via gluconeogenesis to be utilized as fuel for the body. If you were to measure your blood lactate as you are reading this, it would probably be around 1.0 mmol. When you begin to run at an easy effort, blood lactate should remain at 1.0-1.2 mmol because the body is able to clear lactate as quickly as it is being produced. However, as running speed and intensities increase we eventually cross a threshold where lactate clearance cannot keep up with lactate production. First the body crosses the aerobic threshold or LT1, the first threshold where blood lactate increases above baseline (typically around 2.0 mmol). As intensity increases, we reach anaerobic threshold or LT2 where lactate accumulation begins to increase exponentially.
Lactate threshold is the speed of running just below the intensity where lactate accumulation begins to increase exponentially. As long as you stay below this threshold, lactate accumulation is at a steady state in the body. If we go any slower lactate goes away, and if we go any faster we experience significant fatigue as lactate levels climb. Typically this effort falls around 80-90% of max heart rate, or about 10-20s per mile slower than 10k race pace. A well-trained runner can maintain this intensity for about one hour.
Training at this intensity will improve the body’s ability to clear lactate and prevent excessive accumulation. Over time, your threshold will shift to enable you to maintain higher speeds while keeping blood lactate at a steady state. Threshold training should feel comfortably hard aimed at improving endurance.
Interval
Training sessions at interval pace are aimed at maximizing aerobic power, increasing the delivery of blood and oxygen to the working muscle and improving the capacity of the muscle to utilize oxygen. VO2 max is the maximal volume of oxygen that can be utilized by the working muscle. This is your aerobic ceiling as a runner. Beyond this intensity, the body will continue drawing in more and more oxygen but the muscle cannot use the additional oxygen – the effort becomes anaerobic at this point.
Interval training is a high intensity effort, greater than 90% of max heart rate with aims to improve VO2 max. Interval pace should be slightly faster than 5k race pace, a pace you can hold for 10-15 minutes in a race situation. Because of the intensity and speed, intervals should last no longer than 5 minutes in duration. This is to avoid excessive lactate accumulation and fatigue, which might prevent a runner from completing the workout as prescribed. The recovery time should be about equal to the work-bout. For example, if you are running 10x400m at 90 seconds per lap you should rest for about 90 seconds between intervals. This recovery period can be taken as active recovery, an easy jog to allow the body to clear blood lactate and keep the body warm for the next interval.
Remember, the purpose of this workout is to stress and improve VO2 max. Interval training allows you to reach maximal aerobic capacity while achieving the necessary rest periods to accumulate a lot of volume of work. Even though you can run the first few intervals of a workout faster than interval pace, does not mean you should. Overreaching during the first few reps can compromise the remainder of the workout significantly.
This graph shows that to reap the benefits of interval training, the recovery periods must be kept appropriately short. Adapted from Karlssen, J. et al. 1970. Energikraven vid Löpning. Stockholm: Trygg, 41.
Repetition
Also known as “fast reps” or “critical velocity”, the aim of running at this pace is to improve running mechanics and power. Now we are getting into anaerobic work, without oxygen, where the purpose is NOT to develop the aerobic energy system. By running fast reps, you train the body to recruit more muscle fibers which yields more economical running. Plus you learn to sustain paces much faster than race pace, and learn to run relaxed as you run fast. Because this is an anaerobic intensity and the goal is to run fast with good technique, recoveries should be 3-4x as long as the work period.
Hill sprints and strides would fall in this category. These types of effort can be implemented at the end of an easy aerobic run as strides (ie. 6 x :20 accelerations with full recovery). Fast reps can be their own critical velocity workout (ie. 12x200m fast reps with full recovery). Fast reps can also be incorporated into the middle sections of a general aerobic run as surges (ie. 5 mile easy run with 2x :20 surges per mile). There are a lot of ways to incorporate this type of effort into your running to help improve running mechanics and muscular power. The key is to remember the intent: quality running at high speeds requires full recovery. Without adequate recovery we end up somewhere between interval running and fast reps running, and we do not achieve the goal of either.
Finale
The key to getting the most out of yourself as a runner lies in understanding the purpose behind different types of training runs – some level of intentionality is essential for any runner looking to improve and meet their goals. Each run, from easy aerobic efforts to challenging interval and repetition sessions, serves a distinct role in building endurance, speed, and strength. Whether you’re training for a race or simply striving to be a better version of yourself, being deliberate with your training can help you achieve your goals more effectively. By embracing the specific intent of each run, you can optimize your training plan and continue progressing as a well-rounded athlete. Remember, every run serves a purpose—identify yours and train accordingly.
