H.I.I.T. Vs Cardio


Do you suffer from being Time Poor? ⏰

Are you tired of doing continuous hours of Cardio with little to no result? 💦

If this sounds like you and you simply just LOVE cardio, it may be time to start considering the alternative form of cardio giving you more 'bang for your buck' in half the amount of time.

You read correct.

But before we dive in, let's base the question:

Is cardio necessary for general fitness? 🤔

Cardio is a great tool for improving overall cardiovascular fitness and helping establish a base level of general fitness. Fitness is also an important component and general indicator of one's overall health.

Did you know? cardio can also be used to decrease the amount of caloric deficit required from dieting alone.

According to research Physical activity and fitness improves a wide range of physiological factors. Some of these are associated with adiposity, including increasing insulin sensitivity, reducing inflammation, and improving body composition i.e. reduction in fat mass, increased fat-free mass etc[13].

Aerobic exercise and effort is a mode that gets easier to adapt to because of this^. Resistance (Weights) Training however is another great exercise tool to further help and improve body composition, general fitness and strength[2].

More on this later.

What is H.I.I.T.?

H.I.I.T. - standing for High Intensity Interval Training, is fast becoming very popular in the aerobic fitness world. Put simply it incorporates several blocks of short burst 'all-out' effort (10-30 seconds) followed by several minutes of recovery.

According to a study by Metcalfe et al.[3] H.I.I.T. seems to be the most time efficient exercise strategy as it produces a greater amount of workload in a lesser amount of time. The study deduced performing even the minimal amount of exercise for improving 'metabolic health' i.e. 3 x p.w. was enough to induce fat loss in a time efficient manner.

H.I.I.T. also has many variations including: Walking, Jogging, Running, Cycling, Swimming, Rowing etc. Most if not all of these variations will generally result in greater amounts of energy expenditure than time equated forms of cardio i.e. L.I.S.S.[1].

When it comes down to it, if balancing your time, health and physique commitments is of importance, exercising at a higher intensity over a shorter time frame can be beneficial.

Cardio and H.I.I.T.?

Ok, so there are 3 primarily known variations of Cardio Intensity:

L.I.S.S. (Low Intensity Steady State) – Walking or Cycling at typically less than 40% of your Max effort.

M.I.S.S. (Moderate Intensity Steady State) – Walking, Jogging, Elliptical etc. Intensity can increase typically to about 70% of your Max effort.

H.I.I.T. (High Intensity Interval Training) – short bursts of intense activity (80%+ Max Effort) typically followed by a period of active recovery at a lower intensity. General rule of thumb is a work/rest ratio of 1:1 or 1:2.

Traditional cardio aka 'steady state', is generally always performed at a low Intensity for a slightly longer duration of time. H.I.I.T. however is almost always performed at a much higher Intensity at shorter duration periods of time than traditional Cardio.

One key difference is the focus of and utilization of differing Energy systems. Oxygen works as the primary energy system for the body whilst undergoing most forms of Cardio. Secondary to this, fatty acids can also be used for fuel. As Intensity increases the focus shifts to Energy stores i.e. Dietary Fats[17].

Note: athletes whom perform H.I.I.T. can also benefit from incorporating dietary Fats into the Diet.

Advantages for Fat loss?

Much like Cardio, H.I.I.T. can be performed almost anywhere. The flexibility in cardio modes means you are more likely to be able to exercise as you're not restricted by time, equipment and / or location.

An important element of incorporating cardio is to further aid fat loss (energy expenditure). Interval training is promoted more than traditional cardio because of the calories burned both intra and post training.

H.I.I.T. it seems may not always burn a significant amount of calories post exercise than once thought according to further research.

According to a paper published in the Journal of Strength and Conditioning Research. They compared Caloric Expenditure of Aerobic, Resistance, or Combined High-Intensity Interval Training + Resistance in Healthy Men:

They surmised that whilst caloric expenditure was typically greater where concentric exercise protocols i.e. running, biking and / or Resistance training was followed. Hydraulic based exercises involving both Resistance Training + Cardiovascular was slightly as efficient if not greater at expending calories as opposed to endurance training[18].

A past study compared overall energy expenditure (Cardio Vs H.I.I.T.) both during and post exercise. The results post exercise were negligible and only subtle with the Cardio group burning 32kcal whilst the H.I.I.T. group burned 64kcal post exercise[14].

Another study concluded that aerobic exercise performed in the fasted state induces higher fat oxidation than exercise performed in a fed state[16]. These results also line-up with a recent meta-analysis where H.I.I.T. and cardio had similar effects on overall body composition changes[15].

Research from the University of Lethbridge suggests that performing H.I.I.T. at a frequency of 3 x times per week was enough to reduce both body fat and waist circumference.[7]

A further study however seemed to support the notion of H.I.I.T. over cardio leading to significant decreases in central abdominal fat vs a steady state group with little to no changes in abdominal fat[4].

To quote the study conclusion:

“The high intensity interval training produced a greater fat reduction effect compared to steady state intensity, this supports the results from Tremblay et al. Despite exercising half the time, H.I.I.T. subjects in the present study lost 11.2% of total fat mass with steady state subjects experiencing no fat loss. Collectively, these results demonstrate that intermittent sprinting compared to steady state is a more effective and efficient way of controlling body composition.”

Advantages for Muscle Gain and/or retention?

Another important component of dieting in particular for competitors, elite athletes and general sports performance, is the retention of muscle and lean body mass. Generally speaking, the more muscle mass we have the higher our metabolic rate will be.

It is believed once calories decrease or once cardio activity starts to exacerbate, we become subject to loss of lean body mass. There is evidence that meeting dietary protein requirements of 1-1.3g or 1.3-1.8g per lb of bodyweight not only maximizes muscular hypertrophy but aids in the prevention of muscle loss[5].

However, further evidence supports the use of H.I.I.T. for not only muscle retention but also lean muscle gain. According to a study by Trapp et al.[4] it showed subjects in the high intensity interval group gained lean mass in their legs compared to the steady state intensity and control group.

Another study by Wilson et al.[6] found that L.I.S.S. caused more muscle loss than H.I.I.T. To quote the study conclusion::

"H.I.I.T. caused more muscle retention because when you are doing L.I.S.S. (say fast paced walking) you’re not activating muscles the same way as if you were lifting weights. So when you sprint you have hip flexion, knee extension, and these are all weightlifting movements. Think squats, leg presses, leg extensions, etc. H.I.I.T. is another way to overload the muscle and activate the type II muscle fibers."

Cardio + Resistance Training?

Now you're probably wondering which activity mode is the superior? Going by current research we know about 1hr of Resistance training can cause about 150 - 500 kcals in energy expenditure[19]. Even 1 hour of intense Resistance training can burn around ~1000kcals give or take.

However lets ask the more prevalent question; what about Cardio and Weights training?

Is it possible to combine the 2 opposing exercise methods? And more importantly, does it matter if one exercise method is performed before the other?

We now have some good clues on this according to a past study exploring the effects of 'spot-reduction' between both exercise protocols. In this study not only did they discover some great applications / takeaways, but evidence to suggest when is best to perform said exercise.

The intention of the unique study setup was to determine whether performing L.I.S.S. cardio after resistance training results in more fat oxidation[8].

Firstly lets look at the study, individuals were split into 2 groups:

Group 1: performed upper body resistance training + lower body steady state cardio

Group 2: performed lower body resistance training + upper body steady state cardio

Localized fat loss specific resistance trained areas were significant between both groups. The most likely issue and key variable found in the unique study setup was blood flow. It has long been hypothesized that fat mobilization is hampered to a degree from poor blood flow[9].

It's also been demonstrated that exercising causes increased blood flow to nearby localized adipose tissue[10]. Thus further supporting evidence of increased mobilization of local adipose tissue.

However fat mobilization doesn't mean = automatically oxidized aka 'burned off' post training. If fatty acids after entering the bloodstream aren't burned off, there is nothing to prevent it from being stored again[11].

According to research however, if L.I.S.S. is performed post resistance training (after localized free-fatty acids enter the bloodstream) they would likely be used as fuel and oxidized.[12]

Summary

In contrast to previous research, it appears there is added benefits of not only incorporating cardio alongside resistance training, but also the importance of timing.

If you're an avid Weights & Cardio enthusiast, implementing some form of cardio alongside your Resistance training may be one of the best ways to improve and complement your current regime:

Note: As it is recommended to undertake this particular exercise method to expedite the Fat Loss process. It is also generally (not) recommended to exceed overall Frequency. Excessive utilization of HIIT alongside other exercise methods used exacerbately can be detrimental and lead to loss of Lean Muscle Mass and Metabolic fatigue.

References:

1. T, Shields et al, 2012. Effects of aerobic and/or resistance training on body mass and fat mass in overweight or obese adults. Journal of Applied Physiology. Vol113(12):p1831–1837. https://www.ncbi.nlm.nih.gov/pubmed/23019316

2. E, Sanal et al, 2013. Effects of aerobic or combined aerobic resistance exercise on body composition in overweight and obese adults: gender differences. A randomized intervention study. European Journal Physiology & Rehabilitation Medicine.Vol49(1): 2013:1-11. https://www.ncbi.nlm.nih.gov/pubmed/22569489

3. Metcalfe et al. Towards the minimal amount of exercise for improving metabolic health: beneficial effects of reduced-exertion high-intensity interval training. European J applied Physio. 2011. https://www.ncbi.nlm.nih.gov/pubmed/22124524

4. Trapp et al. The effects of high intensity intermittent exercise training on fat loss and fasting insulin levels of young women. Int J of Obesity. 2008

https://www.ncbi.nlm.nih.gov/pubmed/18197184

5. Phillips SM, Van Loon LJ. Dietary protein for athletes: from requirements to optimum adaptation. J Sports Sci. 2011;29 Suppl 1:S29-38. doi: 10.1080/02640414.2011.619204. https://www.ncbi.nlm.nih.gov/pubmed/22150425

6. Wilson, et al. Concurrent Training: A Meta-Analysis Examining Interference of Aerobic and Resistance Exercise. University of Tampa, FL. J Strength Conditioning.

https://www.ncbi.nlm.nih.gov/pubmed/22002517

7. Hazell et al. Run sprint interval training induces fat loss in women. 2014.

https://www.ncbi.nlm.nih.gov/pubmed/24905559

8. J Sports Med Phys Fitness. 2017 Jun;57(6):794-801. doi: 10.23736/S0022-4707.16.06358-1.Effect of combined resistance and endurance exercise training on regional fat loss.

https://www.ncbi.nlm.nih.gov/pubmed/28497942

9. Eur J Appl Physiol Occup Physiol. 1979;42(4):271-81.The effect of unilateral isokinetic strength training on local adipose and muscle tissue morphology, thickness, and enzymes. https://www.ncbi.nlm.nih.gov/pubmed/161225

10. J Strength Cond Res. 2013 Aug;27(8):2219-24. doi: 10.1519/JSC.0b013e31827e8681.Regional fat changes induced by localized muscle endurance resistance training. https://www.ncbi.nlm.nih.gov/pubmed/23222084

11. J Strength Cond Res. 2011 Sep;25(9):2559-64. doi: 10.1519/JSC.0b013e3181fb4a46.The effect of abdominal exercise on abdominal fat. https://www.ncbi.nlm.nih.gov/pubmed/21804427

12. Am J Physiol Endocrinol Metab. 2007 Feb;292(2):E394-9. Epub 2006 Sep 19.Are blood flow and lipolysis in subcutaneous adipose tissue influenced by contractions in adjacent muscles in humans? https://www.ncbi.nlm.nih.gov/pubmed/16985258

13. BMJ Open Sport Exerc Med. 2016; 2(1): e000143. Published online 2017 Mar 1. doi: 10.1136/bmjsem-2016-000143PMCID: PMC5569266PMID: 28879026Update on the effects of physical activity on insulin sensitivity in humans.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5569266/

14. J Appl Physiol (1985). 1997 Feb;82(2):661-6.Comparison of energy expenditure elevations after submaximal and supramaximal running.

https://www.ncbi.nlm.nih.gov/pubmed/9049750

15. Obes Rev. 2017 Aug;18(8):943-964. doi: 10.1111/obr.12536. Epub 2017 May 17.A systematic review and meta-analysis of interval training versus moderate-intensity continuous training on body adiposity.

https://www.ncbi.nlm.nih.gov/pubmed/28513103

16. Br J Nutr. 2016 Oct;116(7):1153-1164. Epub 2016 Sep 9.

Effects of aerobic exercise performed in fasted v. fed state on fat and carbohydrate metabolism in adults: a systematic review and meta-analysis.

https://www.ncbi.nlm.nih.gov/pubmed/27609363

17. Appl Physiol Nutr Metab. 2008 Dec;33(6):1112-23. doi: 10.1139/H08-097.High-intensity aerobic interval training increases fat and carbohydrate metabolic capacities in human skeletal muscle.

https://www.ncbi.nlm.nih.gov/pubmed/19088769

18. J Strength Cond Res. 2015 Mar;29(3):779-85. doi: 10.1519/JSC.0000000000000661.Caloric expenditure of aerobic, resistance, or combined high-intensity interval training using a hydraulic resistance system in healthy men. https://www.ncbi.nlm.nih.gov/pubmed/25162652

19. Energy cost of isolated resistance exercises across low- to high-intensities

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5524349/

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