Why would cardio benefit a lifter?
Just because you’re out of breath and breathing hard after a set of squats, doesn’t mean you're doing cardio. There is a difference between breathing hard and getting your heart rate up after a set vs keeping your heart rate up over a much longer period of time such as with a steady bike ride or jog.
If you are better conditioned there are benefits that can carry over to your lifting. For one, you'll increase your ability to handle and do more volume which can lead to more gains in strength and hypertrophy. You can also recover better between sets so you may not have to rest as long before the next set. This can allow more work to be done in the same time period and quicker workouts if need be. If you can get your workouts in a shorter amount of time, then you can get more effective work in when your training time is limited. Adding in some cardio is a low hanging fruit that lifters can implement to help to improve pain, overall health, and training capacity.
Doing both aerobic and anaerobic exercise (cardio and lifting) together can really be of benefit to you even as someone who is solely focused on lifting. It appears that benefits outside of muscle strength and function from combined lifting and cardio are better than either type in isolation. (5) You will be a healthier person outside of your lifting goals if you do both cardio and lifting, rather than lifting alone. You get better overall effects from combining them vs only lifting.
The main thing to keep in mind with any research that shows negative effects on lifting from aerobic training is that it is usually looking at short term effects which cannot necessarily be extrapolated to long term development. The major issue here is not accounting for adaptation over time. It is likely that once you adapt to the addition of cardio to your lifting, you will make progress and likely better long-term progress the more conditioned you become.
The Interference effect:
This is the big reason why we tend to believe that cardio/aerobic exercise is bad for lifting. The interference effect posits that aerobic training will negatively affect and impede performance, gains and adaptations from lifting. What does research show?
Strength improvements have been shown to be unaffected by concurrent training and an updated meta-analysis found concurrent aerobic and strength training did not interfere with the development of maximal strength and muscle hypertrophy compared with strength training alone, and that the overall risk of interference effects is rather low. (4,5). Further, no significant effects were found with the type of aerobic training (cycling vs. running), frequency of concurrent training (> 5 vs. < 5 weekly sessions), training status (untrained vs. active), and age. (5)
The main factor that could be negatively affected from cardio/aerobic training is explosive strength/power that requires rapid neural activation. (5) Olympic lifts, plyometrics and sprinting may be affected, but appropriately managing your training schedule and volumes to allow for the best recovery and adaptation can help to mitigate this.
Cardio and Strength:
The bottom line is that research on cardio/aerobic training’s effects on strength has found that it does not impede strength gains compared to strength training alone (3). There are some factors and instances that could affect your strength training in the short term that may need to be considered, but they likely are not that important and won’t hinder you long term as long as you are getting all of your strength training stimulus consistently. We need to keep in mind that training is about providing stress and stimulus, thus if there is an effect on your strength training due to fatigue from cardio it likely doesn’t matter as long as the strength stimulus is provided via autoregulation (ensuring the appropriate intensity/weight on the bar and volume for your current state is met) (4). Importantly: we adapt to imposed demands, thus as you get more adjusted to cardio along with strength training you will improve in both areas with minimized deleterious effects, even if you run before lifting.
There are some factors that could potentially affect strength in the short term, and may be factors to consider when setting up your training plan (although I would not live and die by these). One factor is the type of cardio you do and how it affects the specific muscles you will be training after. (4) So, squatting after a run or a bike ride may be impacted more than benching. Another potential impact is decreased strength performance up to 8 hours after aerobic training, (4). If you can separate your lifting and conditioning by several hours this may be better, however, these are acute findings and cannot necessarily be extrapolated to impacts on long-term development (4). Maximal strength development can be impaired if the overall aerobic training volume is high. (5) Basically if you start doing a bunch of cardio that is well above and beyond what you currently can tolerate and recover from, then this will affect your strength at least in the short term. Kinda duh huh? As with any and all training, you need an appropriate dose that you can tolerate and recover from that gradually progresses as your potential increases. Too much and you don’t respond well.
In terms of aerobic training intensity, there does not appear to be any difference in recovery on strength whether the aerobic exercise is high-intensity interval or submaximal continuous training. (4) This is good news as you have some freedom to choose how you want to do your aerobic training. And if you don’t have time to do longer, continuous training, then you could opt for high-intensity intervals in a shorter amount of time to get effective cardio training without any more or worse effect on strength than if you did a long, slow jog or bike ride and vice versa.
Cardio and Hypertrophy:
Cardio/aerobic training has a limited effect on muscle hypertrophy and both cardio and lifting have been found to be beneficial for improving muscle mass, strength, and function. (3) Research has found that combining aerobic and hypertrophy focused training improved thigh and chest girth, proving that aerobic training does not oppose the effects of hypertrophy training and instead can facilitate these if resistance and aerobic training are combined in the right proportions. (3)
Training volume is a crucial component of hypertrophy training. If you are better conditioned, then you can perform and handle more training volume which will yield better hypertrophy. The better shape you’re in, the more you can do which yields more hypertrophy stimulus.
Why would cardio benefit rehab?
A good way to develop pain is to be physically inactive, and an antidote is exercise. (1) Conditions such as low back pain, osteoarthritis, and fibromyalgia are significantly impacted by both strengthening AND aerobic exercise. (1) Also, aerobic exercise reduces pain sensitization in individuals with musculoskeletal pain. (6)
Think about it like this: you’re lifting heavy 3 or more days/week with each session being a grind and you’re dealing with nagging pain issues. What if you add in a few walks or bike rides throughout the week which won’t negatively affect your lifting, especially in the long run, and there is a good chance it may help with the pain you’re dealing with? As lifters we tend to be a little too one-sided and specific with exercise so expanding a little bit to include some low intensity cardio, even at a low volume can be very beneficial. We are so tied to numbers and performance with our lifting; wouldn’t it be nice to do some other form of exercise where you don’t have to worry about how you perform? Just go and get an easy to moderate walk/bike ride/jog in without having any mental stress about the performance attached to it.
If you’re injured or dealing with a disruptive pain issue where you can’t train normally, performing aerobic/cardio exercise would be a good way to potentially substitute your overall training volume and give you a way to do something that is less pain provoking. It’s likely to help improve your pain, improve your capacity which can also allow for more training volume later on which is likely to lead to better gains, and it will help with your overall health. There are a lot of options to fit your needs and preferences with aerobic exercise. (2) You can get pain relieving effects both immediately and long term from aerobic exercise. (6)
Exercise reduces the sensitivity to noxious stimuli through a process called exercise-induced hypoalgesia (EIH). Three types of exercise produce EIH effects: aerobic, dynamic resistance, and isometric contraction exercise (2) So, if you lift AND do conditioning then you have more than one form of exercise that can produce some pain reducing effects. (2)
Effects on the nervous and immune systems:
Aerobic exercise may provide a protective effect against pain. Central nervous and immune systems are changed in a way that may provide a protective effect, and these changes are not found in inactive individuals which would further suggest this occurs. (1) Aerobic exercise may reduce pain by reducing pain sensitization through pain inhibitory mechanisms and/or endogenous opioid and cannabinoid systems in people experiencing musculoskeletal pain. (6).
Effects on pain outside of the musculoskeletal system:
The positive mental and psychological effects of regular exercise cannot be understated. Pain has far more factors beyond the physical body, thus anything that also affects these other areas can positively affect pain. (1) The emotional response to pain can be a large factor and contributor to an individual’s pain experience and aerobic exercise may impact this more than the actual pain perception. (2) How you feel about the pain may be positively impacted more than the pain you actually feel. Even though you still feel the pain, you may not react to it the same and have less negative emotions towards it which can improve your whole pain experience.
Chronic pain:
The systemic inflammation that is associated with chronic pain may also be reduced through aerobic exercise. (1) However, chronic pain can be a stubborn and tricky situation to positively change. Even with all of the benefits of exercise, particularly aerobic exercise discussed in this article, some people will actually experience increased pain sensitivity with exercise as the exercise induced hypoalgesic effects are weakened or even reversed. (2) Not all individuals experiencing chronic pain will experience the same response to aerobic exercise. (6) This is where individualizing training as well as paying attention to the nature of the pain response is really important. If the pain is present but is tolerable enough to keep going, then it is worth continuing to see if this gradually desensitizes. Guidelines and protocols for aerobic exercise, especially for pain reduction should not be applied blindly and the exercise type, intensity, duration, etc needs to all be adjusted to something the individual can repeatedly tolerate, even if it does not fall within what is recommended. Over time, probably a long period of time, the pain will start to improve and then we can worry about hitting those guidelines.
Intensity of aerobic exercise:
There does appear to be a threshold you have to achieve with aerobic exercise intensity to positively affect pain: 70% maximal oxygen uptake [VO (2) max]. (2) As intensity increases, the effect of exercise induced hypoalgesia increases with more intense exercise producing larger effects. (2) So, the harder you want to push it, the better effect you’ll get provided you tolerate it.
Low intensity aerobic exercise can inhibit negative emotional pain response while moderate intensity reduces the pain sensitivity to various painful stimuli. (2). So, you may still get some pain relieving effect from aerobic exercise that is below 70% which is good news if your pain situation prohibits you from any form of aerobic exercise to a high enough intensity. Such as with chronic pain discussed above or an acute pain situation that is highly sensitized.
Ways to implement cardio/aerobic training into your lifting:
The World Health Organization Physical Activity Guidelines for Adults is as follows:
“Adults should do at least 150–300 minutes of moderate-intensity aerobic physical activity; or at least 75–150 minutes of vigorous-intensity aerobic physical activity; or an equivalent combination of moderate- and vigorous-intensity activity throughout the week, for substantial health benefits”
It is certainly tricky to fit all this in during the week along with your normal lifting routine, especially if you are a working parent. The main thing to keep in mind is to add in what your schedule allows. Even if it is only a little bit.
Some practical recommendations:
Aim for at least 2x/week, more if you can
Do whatever your time and tolerance allows. If you haven’t done any cardio consistently, then a couple 5-10 minute bike rides or jog/walks can be a great place to start. Even if you only have 5 minutes you could knock out some intense, short intervals that will really get your heart rate up and give you a good cardio training stimulus.
If you have less than about 10 minutes, do higher intensity intervals where you really push the intervals hard. If you have more than 10 minutes then do low to moderate intensity steady state conditioning at 5-7/10 RPE or 60-70% max HR.
For short and high intensity intervals, I would aim for 1:1 or up to 1:3 work to rest ratio in whatever time you have available. Push the work intervals hard, and take it easy during the rest interval. Examples: air bike intervals 30 seconds on, 30 to 90 seconds rest for 8 or more minutes, run 15 seconds, walk 45 seconds for 10 rounds or more.
You can do a mix of intervals and steady state throughout the week and even combine them in the same session, just do what you can and prefer.
It doesn’t really matter when you do it either. Most optimally would be a different time of day than your lifting or on a non-lifting day, but doesn’t have to be especially if your schedule doesn’t allow for this. You can do it before or after your lifting as well. After lifting is probably better, especially if doing intervals, but if you can handle it and if it’s just what you have to do, then doing conditioning before lifting can be fine. Remember, you can adapt and getting in the training stimulus is what is important, not the short term performance.
References:
Sluka KA, Frey-Law L, Hoeger Bement M. Exercise-induced pain and analgesia? Underlying mechanisms and clinical translation. Pain. 2018 Sep;159 Suppl 1(Suppl 1):S91-S97. doi: 10.1097/j.pain.0000000000001235. PMID: 30113953; PMCID: PMC6097240.
Zheng K, Chen C, Yang S, Wang X. Aerobic Exercise Attenuates Pain Sensitivity: An Event-Related Potential Study. Front Neurosci. 2021 Sep 21;15:735470. doi: 10.3389/fnins.2021.735470. PMID: 34630022; PMCID: PMC8494006.
Tan J, Krasilshchikov O, Kuan G, Hashim HA, Aldhahi MI, Al-Mhanna SB, Badicu G. The Effects of Combining Aerobic and Heavy Resistance Training on Body Composition, Muscle Hypertrophy, and Exercise Satisfaction in Physically Active Adults. Healthcare (Basel). 2023 Aug 31;11(17):2443. doi: 10.3390/healthcare11172443. PMID: 37685476; PMCID: PMC10487730
SPORER, BEN C.; WENGER, HOWARD A.. Effects of Aerobic Exercise on Strength Performance Following Various Periods of Recovery. Journal of Strength and Conditioning Research 17(4):p 638-644, November 2003.
Schumann M, Feuerbacher JF, Sünkeler M, Freitag N, Rønnestad BR, Doma K, Lundberg TR. Compatibility of Concurrent Aerobic and Strength Training for Skeletal Muscle Size and Function: An Updated Systematic Review and Meta-Analysis. Sports Med. 2022 Mar;52(3):601-612. doi: 10.1007/s40279-021-01587-7. Epub 2021 Nov 10. PMID: 34757594; PMCID: PMC8891239.
Tan L, Cicuttini FM, Fairley J, Romero L, Estee M, Hussain SM, Urquhart DM. Does aerobic exercise effect pain sensitisation in individuals with musculoskeletal pain? A systematic review. BMC Musculoskelet Disord. 2022 Feb 3;23(1):113. doi: 10.1186/s12891-022-05047-9. PMID: 35114987; PMCID: PMC8815215.
Additional References and Further Reading:
Research Spotlight: The interference effect is getting less scary by the day • Stronger by Science
Can cardio (eventually) make you bigger? • Stronger by Science