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Writing workouts and creating meal plans is tough. There are many training variables to account for, like dietary needs, previous injuries, and goals. Programming is a blend of art and science, which is why you’ll be paying $50 to $500 an hour for a fitness professional to create a plan for you.
But you’ve probably heard the buzz about ChatGPT and AI chatbots.
Can ChatGPT create your workout plans for free? Yes, ChatGPT can help you create a workout plan that you could use to gain strength. Or you could ask it to create a more specific workout plan about your goal. You can continue to ask it questions to further refine it as you progress. But ChatGPT’s ability to account for all training variables is limited and should be used with caution.
Here’s the problem, how do you know if the workout program ChatGPT created is good or not? That’s where I come in to help.
I’ve been training folks for over a decade from all walks of life. I’m a gym owner and head trainer and I asked ChatGPT to create 8 strength training programs to see how it would help you gain strength and muscle mass for weightlifters and powerlifters.
Let’s dive into the pros and cons of ChatGPT-created workouts!
What Is ChatGPT?
ChatGPT is an artificial intelligence (AI) program that draws on information acquired from the internet up to 2021. It is like a Google search in a conversational tone.
While ChatGPT will always produce an answer, it is not always the right answer. Per OpenAI.com, where ChatGPT was created:
“[ChatGPT] has limited knowledge of world and events after 2021 and may also occasionally produce harmful instructions or biased content. We'd recommend checking whether responses from the model are accurate or not.”
The OpenAI.com website is quick to point out ChatGPT is a research preview. In layman’s, it’s a novel tool to help you gather information in a quick and concise manner, but all information gathered should be fact-checked.
But the responses are fast and on first glance look great. So could ChatGPT replace your personal trainer and help you get fit and healthy?
Can ChatGPT Write My Workout Programs?
Yes, workout programs can be generated by this AI program. From a fitness professional's perspective, the training routines created by the AI program are rudimentary.
Here’s my initial conversation with ChatGPT:
Me: Can you create a resistance training program for a novice that lasts one hour?
ChatGPT: Sure! Here's a sample resistance training program for a novice that lasts one hour:
Note: Always remember to warm up before starting the workout.
Warm-up: 5-10 minutes of light cardio (e.g., jobbing, cycling) or dynamic stretching.
Resistance Training:
- Squats (3 sets x 10 reps)
- Push-Ups (3 sets x 10 reps)
- Bent-over rows (3 sets x 10 reps)
- Lunges (3 sets x 10 reps)
- Dumbbell Shoulder Press (3 sets x 10 reps)
- Plank (3 sets, hold for 30 seconds each)
Cool-down: 5-10 minutes of light cardio (e.g. walking) or static stretching.
Remember, the key to progress in resistance training is to gradually increase the intensity (e.g., weight lifted), volume (e.g., number of sets/reps), or difficulty (e.g., variation of exercises) over time. Also, always make sure to use proper form and technique to avoid injury.
At first glance, this would be a perfectly fine routine for someone who does not have any injuries or movement restrictions right out of the gate. In addition to the exercises listed, ChatGPT also provided a brief description of how to do each exercise.
This is a rudimentary training program though and for the sake of learning, I decided to dig a little deeper and see what ChatGPT could whip up for using different criteria and making specific training requests.
Want to learn more about programming your own workouts? Check out this 3-day split article.
Pros and Cons of ChatGPT Workouts
Here's a quick overview of the benefits and drawbacks of creating ChatGPT workouts.
Pros
Can Write Generic Workouts In Seconds
For novice lifters with no previous injuries or medical issues, a simple workout program will get you started.
Can Make Modifications To Generic Workouts
If you know what questions to ask and what to modify, you can hypothetically create a more specific and effective training program.
Draws From A Massive Information Pool
ChatGPT is using information from sites like Wikipedia, blogs, and archived books all from the internet, up to 2021.
Can Train AI To Write Better Workout Templates
If you know what questions to ask and what variables to modify you could teach ChatGPT to consistently write better workouts.
Cons
Cannot Watch Your Form
There are performance points a seasoned trainer can spot quickly in a few well-prescribed exercises. In a squat, for example, a trainer can tell whether or not your glutes are engaging based on what your feet and knees are doing.
Cannot Account For Individual Movement Patterns
Everybody’s body is different. Squat stances vary dramatically based on the position of your hip bones. ChatGPT cannot, yet, assess your form and make the appropriate recommendations to help you get stronger and prevent injury. A trainer can make adaptations to the program on-the-fly depending on how the client feels on any given day.
Cannot Provide The “Human Touch”
Motivation, feedback, and critique are all variables a person needs to thrive in any training program. AI-generated workout programs only provide you with exercises, sets, reps, and rest times. ChatGPT will not call you when you miss a workout and ask why you missed the training session. AI cannot tell when to decrease your weight or reps after a bad night's sleep. There is no way for ChatGPT to give you positive feedback mid-training session for good reps. It is after all artificial intelligence.
Must Know The Right Questions To Ask
The people at OpenAI have created a powerful tool, but if you’re not sure what to ask to progress to the next level, you’re not going anywhere. Back to the analogy earlier, just because you have a calculator doesn’t guarantee you’ll know the right equation to figure out the area of a circle.
Data Limitations
Per the OpenAI website: “May occasionally generate incorrect information. May occasionally produce harmful instructions or biased content. Limited knowledge of world and events after 2021”
No Midline Training
In all the workouts we created there was little to no mention of midline training. Core stability is a critical element of any workout program. Yes, technically every workout should be a midline exercise, but how would a novice know that without being told?
Check out this article on How To Work Your Core With Proper Plank Form.
8 Strength Workouts Created By ChatGPT
We found out AI can certainly write a rudimentary workout program, but what if we add more filters, variables, and stipulations?
Can ChatGPT write a decent powerlifting program? Or a bodybuilding program?
- Can it account for a shoulder and knee injury?
- Additionally, a one-off workout is easy enough, but can ChatGPT write a whole week’s worth of workouts for a powerlifter?
- Can AI create a week’s worth of workouts tailored for a specific individual?
We’re going to dive deeper into the world of AI and see how robust this artificial intelligence truly is.
Here is a list of the 8 additional workouts ChatGPT created to answer my questions.
- One-hour powerlifting routine
- Powerlifting routine with single joint assistance exercises
- Powerlifting routine in 30 minutes
- Powerlifting routine with a shoulder injury
- Powerlifting routine with knee pain
- One-hour bodybuilding routine
- One-week powerlifting routine
- One-week powerlifting routine for an individual
After each workout, I’ll provide a brief description of the pros and cons of each AI-generated workout.
AI-Generated Workouts
One-Hour Powerlifting Routine
As a powerliftingtechnique.com reader you know the sets and reps given by ChatGPT in my first conversation with the program won’t cut it for strength gains. Here is how ChatGPT modified the program to accommodate someone with a powerlifting goal in mind.
Exercise | Sets x Reps | Rest Between Sets |
Squats | 5 x 3 | 2-3 minutes |
Bench Press | 5 x 3 | 2-3 minutes |
Deadlifts | 5 x 3 | 2-3 minutes |
Pull-ups | 3 x 8 | 1-2 minutes |
Dumbbell Rows | 3 x 8 | 1-2 minutes |
Plank | 3 x 30 sec | 1-2 minutes |
Remember to warm up before starting your workout, and cool down afterward. Gradually increase the weight lifted over time and use proper form and technique to avoid injury. And don’t forget to vary your exercises, sets, and reps to challenge your muscles in different ways.
At face value, this isn’t a terrible plan. I did not tell ChatGPT to span these exercises throughout the week, which would be ideal, and we’ll do that later. As many powerliftingtechnique.com readers know, you would need to train each of those lifts, at least, a couple of times a week to see meaningful progress.
Powerlifting Routine With Single Joint Assistance Exercises
The first iteration wasn’t too bad, especially for a novice. Some single joint assistance exercises can go a long way in creating healthy, stable joints though. I asked ChatGPT to create a new workout program with a single joint exercise parameter in mind and here’s what it came up with:
Exercise | Sets x Reps | Rest Time |
Barbell Back Squat | 4 x 6 | 2-3 minutes |
Leg Extensions | 3 x 12 | 1-2 minutes |
Barbell Bench Press | 4 x 6 | 2-3 minutes |
Tricep Pushdowns | 3 x 12 | 1-2 minutes |
Barbell Deadlifts | 4 x 6 | 2-3 minutes |
Dumbbell Bicep Curls | 3 x 12 | 1-2 minutes |
Plank | 3 x 30 sec | 30 sec |
Incorporating single-joint assistance exercises can help target specific muscle groups and improve overall strength and powerlifting performance. Remember to vary your exercises, sets, and reps over time to challenge your muscles in different ways and to avoid plateauing.
Decent incorporation of single joint exercises to complement the three major lifts in powerlifting. The reps shifted a bit to the high side of strength training and crept towards hypertrophy, but not the worst modification. The rest times look to be appropriate for each exercise. This training program is definitely a step in the right direction, but pairing a deadlift with a dumbbell bicep curl seems a bit odd.
Powerlifting Routine In 30 Minutes
We all know to truly build strength you have to commit more than 30 minutes worth of training time. In the name of curiosity though, let’s see what kind of powerlifting routine ChatGPT creates for those short on time.
Exercise | Sets x Reps | Rest Time |
Barbell Back Squat | 3 x 6 | 1-2 minutes |
Barbell Bench Press | 3 x 6 | 1-2 minutes |
Barbell Deadlifts | 3 x 6 | 1-2 minutes |
Incorporating compound exercises such as the barbell back squat, bench press, and deadlifts can help target multiple muscle groups and improve overall strength and powerlifting performance. Remember to vary your exercises, sets, and reps over time to challenge your muscles in different ways and to avoid plateauing.
Now is where you can see where ChatGPT starts to unravel. Programming a powerlifting routine for a quick, 30 min session is a tall order anyway, but this plan simply would not work. A 5 min warm-up and cool-down would eat up a third of your training time. Factor in a few warm-up sets to get up to weight for each lift and you’re well above the 30 min threshold, not including rest times.
Again, this would be a tall order for any trainer, so it’s no surprise ChatGPT fell short.
Powerlifting Routine With A Right Shoulder Injury
I intentionally left the shoulder injury vague, I wanted to see what kind of modifications ChatGPT would make. Shoulder injuries are a real-world scenario that a certified fitness professional can navigate with relative ease, depending on the severity of the injury. Here’s what ChatGPT created:
Exercise | Sets x Reps | Rest Time |
Box Squats | 4 x 8-12 | 1-2 min |
Sumo Deadlifts | 4 x 8-12 | 1-2 min |
Dumbbell Floor Press | 4 x 8-12 | 1-2 min |
Seated Cable Rows | 4 x 8-12 | 1-2 min |
Dumbbell Lateral Raise | 3 x 10-15 | 1-2 min |
Hammer Curls | 3 x 10-15 | 1-2 min |
Incorporating exercises such as box squats, sumo deadlifts, and dumbbell floor press can help reduce stress on the shoulders while still targeting major muscle groups. Remember to vary your exercises, sets, and reps over time to challenge your muscles in different ways and to avoid plateauing. If your shoulder injury persists or worsens, it’s important to seek medical advice from a qualified healthcare provider.
The modifications to the training program aren’t terrible. An actual trainer would be able to ask follow-up questions to specify the nature of the shoulder injury though. Odds are dumbbell lateral raise will not bode well for someone with a shoulder injury.
Additionally, the rest times were decreased, which would not allow for a shoulder to recover much even if it was not injured. Also, the rep range increased for some unknown reason.
Powerlifting Routine With Knee Pain
Training around injuries is a part of powerlifting. Not every day is great. A certified fitness professional can help you navigate those waters and help you maintain or increase your strength. Here’s the ChatGPT solution:
Exercise | Sets x Reps | Rest Time |
Box Squats | 4 x 8-12 | 1-2 min |
Romanian Deadlifts | 4 x 8-12 | 1-2 min |
Leg Press | 4 x 10-15 | 1-2 min |
Seated Leg Curls | 4 x 10-15 | 1-2 min |
Glute Bridges | 3 x 12-15 | 1-2 min |
Standing Calf Raises | 3 x 12-15 | 1-2 min |
Incorporating exercises such as box squats, Romanian deadlifts, and leg press can help reduce stress on the knees while still targeting major muscle groups. Additionally, seated leg curls can help strengthen the hamstrings, which can also help with knee pain. Glute bridges and standing calf raises can help strengthen other lower body muscles.
There are definitely some modifications present, but knee injuries can be complex. More follow-up questions are required to figure out what range of motion is acceptable for the individual. Seated leg curls and leg presses may take some pressure off the knee joint, but if bending the knee, in general, hurts you would need further modifications.
Also, the rep range definitely went up to hypertrophy and even muscular endurance rep range. Which may be appropriate for injury recovery, but how would you know that and when should you increase weight and decrease reps? These are all things a certified personal trainer could answer quickly and confidently.
Check out this article for more information about the top 17 squat mistakes.
One-Hour Bodybuilding Routine
Seeing all these hypertrophy rep ranges made me wonder. Can ChatGPT recognize the differences between powerlifting and bodybuilding routines? Powerlifting reps are lower than the reps needed to achieve hypertrophy in a bodybuilding routine. Here’s what ChatGPT created for a bodybuilding goal:
Exercise | Sets x Reps | Rest Time |
Barbell Squats | 4 x 8-12 | 1-2 min |
Barbell Bench Press | 4 x 8-12 | 1-2 min |
Seated Cable Rows | 4 x 8-12 | 1-2 min |
Dumbbell Shoulder Press | 3 x 10-15 | 1-2 min |
Barbell Bicep Curls | 3 x 10-15 | 1-2 min |
Cable Tricep Pushdowns | 3 x 10-15 | 1-2 min |
Incorporating compound exercises such as barbell squats, bench press, and seated cable rows can help target multiple muscle groups and improve overall bodybuilding performance. Remember to vary your exercises, sets, and reps over time to challenge your muscles in different ways and to avoid plateauing. Additionally, make sure to use proper form and technique when performing the exercises to avoid injury.
When it comes to simple training programs as a rudimentary guideline, ChatGPT does an adequate job. The rep ranges listed above and the corresponding rest times are what you may expect from any run-of-the-mill training program.
Do powerlifters train to failure like bodybuilders? Check out this article to learn more.
One-Week Powerlifting Training Program
Everything up to this point has been one-off workouts, nothing someone who seriously trains would likely do in one day. I challenged ChatGPT to create a one-week powerlifting training program for a novice and this is what it created:
Day 1: Upper Body
Exercise | Sets x Reps | Rest Time |
Barbell Bench Press | 4 x 8-10 | 1-2 min |
Barbell Rows | 4 x 8-10 | 1-2 min |
Seated Dumbbell Press | 3 x 10-12 | 1-2 min |
Dumbbell Flys | 3 x 10-12 | 1-2 min |
Bicep Curls | 3 x 10-12 | 1-2 min |
Tricep Extensions | 3 x 10-12 | 1-2 min |
Day 2: Lower Body
Exercise | Sets x Reps | Rest Time |
Barbell Squats | 4 x 8-10 | 1-2 min |
Romanian Deadlifts | 4 x 8-10 | 1-2 min |
Leg Press | 3 x 10-12 | 1-2 min |
Seated Leg Curls | 3 x 10-12 | 1-2 min |
Standing Calf Raises | 3 x 10-12 | 1-2 min |
Day 3: Rest Day
Day 4: Upper Body
Exercise | Sets x Reps | Rest Time |
Dumbbell Bench Press | 4 x 8-10 | 1-2 min |
Chin-Ups | 4 x 8-10 | 1-2 min |
Seated Cable Rows | 3 x 10-12 | 1-2 min |
Dumbbell Lateral Raises | 3 x 10-12 | 1-2 min |
Hammer Curls | 3 x 10-12 | 1-2 min |
Tricep Pushdowns | 3 x 10-12 | 1-2 min |
Day 5: Lower Body
Exercises | Sets x Reps | Rest Time |
Deadlifts | 4 x 8-10 | 1-2 min |
Bulgarian Split Squats | 4 x 8-10 | 1-2 min |
Leg Press | 3 x 10-12 | 1-2 min |
Seated Leg Curls | 3 x 10-12 | 1-2 min |
Standing Calf Raises | 3 x 10-12 | 1-2 min |
Day 6: Rest Day
Day 7: Rest Day
If you were just starting your fitness journey this wouldn’t be a terrible plan. The reps are more in the hypertrophy training range, but if you’re just starting a fitness routine that would not be the worst error made. The plan is definitely generic, and if you had no other resources at your disposal, this would be a decent starting point.
Powerlifting Routine For A Specific Person
I really wanted to test the limits of ChatGPT’s capabilities at this point. I decided to ask the AI to write a week-long powerlifting training program for a 190lb, 5ft 9in, 43-year-old male, with 1 year of lifting experience. Here’s what ChatGPT delivered:
Day 1: Upper Body
Warm-up: 5-10 min of cardio (e.g., rowing, cycling)
Exercises | Sets x Reps | Rest Time |
Barbell Bench Press | 4 x 8-10 | 2-3 min |
Incline Dumbbell Press | 3 x 10-12 | 1-2 min |
Seated Cable Rows | 4 x 8-10 | 2-3 min |
Dumbbell Bicep Curls | 3 x 10-12 | 1-2 min |
Tricep Pushdowns | 3 x 10-12 | 1-2 min |
Day 2: Lower Body
Warm-up: 5-10 min of cardio (e.g., rowing, cycling)
Exercises | Sets x Reps | Rest Time |
Barbell Squats | 4 x 8-10 | 2-3 min |
Romanian Deadlifts | 4 x 8-10 | 2-3 min |
Leg Press | 3 x 10-12 | 1-2 min |
Standing Calf Raises | 3 x 10-12 | 1-2 min |
Day 3: Rest Day
Day 4: Upper Body
Warm-up: 5-10 min of cardio (e.g., rowing, cycling)
Exercises | Sets x Reps | Rest Time |
Dumbbell Bench Press | 4 x 8-10 | 2-3 min |
Pull-Ups or Lat Pulldowns | 4 x 8-10 | 2-3 min |
Seated Dumbbell Press | 3 x 10-12 | 1-2 min |
Dumbbell Flyes | 3 x 10-12 | 1-2 min |
Hammer Curls | 3 x 10-12 | 1-2 min |
Overhead Tricep Extension | 3 x 10-12 | 1-2 min |
Day 5: Lower Body
Warm-up: 5-10 min of cardio (e.g., rowing, cycling)
Exercise | Sets x Reps | Rest Time |
Deadlifts | 4 x 8-10 | 2-3 min |
Bulgarian Split Squats | 4 x 8-10 | 2-3 min |
Leg Press | 3 x 10-12 | 1-2 min |
Seated Leg Curls | 3 x 10-12 | 1-2 min |
Standing Calf Raises | 3 x 10-12 | 1-2 min |
Day 6: Rest Day
Day 7: Rest Day
When you compare the specific program and the more generic week-long program not much changed. Most of the exercises are the exact same. The rest periods changed a little. The sets and reps decreased for a few of the exercises, but overall not any big differences.
The hope was ChatGPT would create some more specificity for a trainee who is starting in their middle-aged years. But both programs are simple and generic. They are better than what you might find on social media, but not as well designed as you would get from an experienced fitness trainer.
Did ChatGPT Forget About Warm-Ups and Cool-Downs?
For the sake of brevity, I left out the following message that appeared after each recommendation:
Note: Always remember to warm up before starting the workout and to cool down after the workout with 5-10 minutes of light cardio (e.g., walking) or static stretching.
When performing the exercises, make sure to use proper form and technique, and to start with a weight that allows you to perform the prescribed reps with good form. Gradually increase the weight lifted over time as you get stronger.
The specific messages relative to the prompt were left under each respective routine.
Can ChatGPT Be My Personal Trainer?
The short answer is no. ChatGPT can write generic workouts for a novice lifter and, with some tweaking, maybe an intermediate lifter.
There are more variables to consider outside of exercise selection, sets, reps, and rest time when it comes to creating a complete training program.
ChatGPT has a number of limitations:
- It cannot watch your form and offer personalized feedback to help you avoid injuries.
- It doesn’t account for individual movement patterns.
- It doesn't provide motivation and accountability.
- It doesn’t offer midline training.
- Additionally, it may produce incorrect or biased content and has limited knowledge of events after 2021.
- You also need to know the right questions to ask when using ChatGPT as a personal trainer. These are questions only a personal trainer would know.
Therefore, ChatGPT is what the calculator was to our grandparents, a great tool that can help you get work done faster. But using a calculator does mean you are now a great mathematician, same for writing workouts.
Creating a basic template does not make you a trainer. There are many nuances a seasoned trainer needs to account for with each client. Nuances that require solutions that are more easily answered with experience.
Should You Use ChatGPT Workouts?
If ChatGPT is your only resource, an AI-generated workout wouldn’t be the worst. Workouts generated by ChatGPT can definitely get a sedentary person off the sofa and move in the right direction.
Those who stick with their training will soon outgrow the generic program though. ChatGPT cannot teach you good form either. All the workouts listed came with basic descriptions of each exercise, but there’s no way the AI can tell if you’re completing the reps well.
Who Should You Use ChatGPT?
ChatGPT is a powerful tool that would be better suited for a fitness professional to use and tweak workouts rather than create a whole new routine from scratch. There are a lot of nuances when it comes to writing a training program.
To someone who is familiar with many of those variables, ChatGPT can be a critical time-saving tool to provide better results for clients who would otherwise spend more time fact-checking than working out.
FAQs
Can ChatGPT Compensate For Injuries?
ChatGPT can create a workout program providing a specific injury is given. Injuries are no light matter though and if you rehabilitate incorrectly you may be setting yourself up for future injuries. It’s best to consult with a professional regarding injuries and lifting.
Check out this article about which squat variation is best for low back pain.
Can ChatGPT write a meal plan for me?
Meal plans can be created, but these plans do not account for individual preferences, food allergies, or budgets. Like the workouts listed above, the meal plans are generic. Seek the help of a registered dietitian if you need dietary help.
Here’s an article to help you figure out how many calories you need to gain muscle.
Does ChatGPT provide its sources?
Yes, but you have to be specific. When I asked the AI what sources it used to create the workout programs above it said it made recommendations from ACSM and NSCA guidelines. If asked for scholarly articles on the benefits of exercise it will provide credible sources, including links to the articles.
Final Thoughts
So can you use ChatGPT for weightlifting? ChatGPT is a novel tool created by OpenAI.com. It can be used to edit photos, write short paragraphs, do quick research, and even write workouts. A certified fitness professional is still your best option when it comes to creating a well-rounded training program.
The pros do not outweigh the cons for ChatGPT to replace your private trainer. The program can only recommend exercises, sets, reps, and rest time. Form and technique cannot be evaluated by AI at this time, a key element in your long-term lifting success. So don’t expect your next training session to be conducted by C-3P0.
Additionally, there are many variables ChatGPT cannot account for including motivation, social interaction, individual anatomical differences, and mood from day to day. All variables a fitness professional can and does account for when creating an optimal training program for each person.
The real question is how do you know ChatGPT didn’t write this article?
About The Author
Trevor Bridges has a BS in Health and Exercise Science and has been training folks how to move pain-free and get stronger for over a decade. He is currently experimenting with different training programs that will make him most like Captain America. When he is not running his gym or creating content, you can usually find him playing with his dogs and praying for shorter summers and longer winters.
Additional Resources:
- Westcott, W. L. (2012). Resistance training is medicine: effects of strength training on health. Current sports medicine reports, 11(4), 209-216. https://journals.lww.com/acsm-csmr/Fulltext/2012/07000/Resistance_Training_Is_Medicine__Effects_of.8.aspx
- Kraemer, W. J., & Ratamess, N. A. (2004). Fundamentals of resistance training: progression and exercise prescription. Medicine and science in sports and exercise, 36(4), 674-688. https://journals.lww.com/acsm-msse/Fulltext/2004/04000/Fundamentals_of_Resistance_Training__Progression.16.aspx
- Peterson, M. D., Rhea, M. R., & Alvar, B. A. (2005). Maximizing strength development in athletes: a meta-analysis to determine the dose-response relationship. The Journal of Strength & Conditioning Research, 19(3), 439-446. https://journals.lww.com/nsca-jscr/Abstract/2005/08000/Maximizing_Strength_Development_in_Athletes__A.3.aspx
- Faigenbaum, A. D., & Myer, G. D. (2010). Resistance training among young athletes: safety, efficacy and injury prevention effects. British journal of sports medicine, 44(1), 56-63. https://bjsm.bmj.com/content/44/1/56.short
- Campos, G. E., Luecke, T. J., Wendeln, H. K., Toma, K., Hagerman, F. C., Murray, T. F., … & Staron, R. S. (2002). Muscular adaptations in response to three different resistance-training regimens: specificity of repetition maximum training zones. European journal of applied physiology, 88(1-2), 50-60. https://link.springer.com/article/10.1007/s00421-002-0681-6