Find out how to avoid sacrificing strength and lean mass while improving aerobic fitness and body composition (reduce body fat percentage)

I often hear people say they need to start doing more cardio (jogging) to shed a couple unwanted pounds.  Is this really the most effective way to reduce body fat, increase or at least maintain lean mass and improve aerobic fitness?  … maybe not… read on to find out why!

What is interval training?

Interval training is simply a method of exercise that uses alternating periods of work to rest.  The work to rest ratios will be dependant on your ultimate goals.

Now, a basic lesson on energy systems.  ATP (adenosine-triphosphate) fuels the metabolic demands of exercise and can be produced anaerobically (without oxygen) or aerobically (with oxygen).

Anaerobic — ATP-PCr: This energy system is used for very short bursts of energy such as jumps and short duration sprints. Creatine phosphate stores typically power the first minute or less of exercise.  Supplementing creatine is one way to maximize this energy system.

Anaerobic — Glycolysis: This energy system supplies energy for exercise lasting up to approximately 2 minutes.  Glycolysis is a process where energy is harvested from glucose and glycogen (stored carbohydrate) and transferred into ATP.  For people who think carbohydrates are the devil … figure it out… for some people low carb diets are great… for others low carb diets are detrimental.  Check out my article on CARBOHYDRATE CONTROVERSY 

Aerobic: The aerobic system is a long-term energy system, by 5 minutes this system is clearly dominating energy production.

Mitch Stewart

KEY POINT:  Yes, there are three distinct energy systems, each dominating certain time frames… but all systems work together… the aerobic system plays a key role in the recovery of the anaerobic systems!  Neglecting to train the aerobic system will result in poor recovery.  Let me explain how the aerobic system works during recovery:

A heavy (high intensity) sled push requires high amounts of ATP in a short period of time, this high rate of energy expenditure does not allow the aerobic system to fully “kick in”… consequently ATP is borrowed (used from anaerobic sources) creating an oxygen debt.  Like any debt it eventually need to be paid back… during the recovery process (between sets) the aerobic system is hard at work doing exactly that.  This process is known as EPOC (excess post-exercise oxygen consumption).   EPOC involves stimulating the aerobic system to produce the large amounts of ATP needed to restore the two anaerobic energy systems.  Poor aerobic fitness will result in less efficient recovery!

Mitch Stewart

Knowing that we can improve aerobic fitness through not only long duration steady state exercise is valuable information for the athlete and every day gym goer…

Avoid sacrificing strength and lean mass while improving aerobic fitness… excessive low intensity steady state cardio will negatively affect strength, power output and lean mass. 

There is a significant amount of research supporting the aerobic improvements through interval training. You may be surprised at minimal volume required to experience improvements in oxygen utilization.  A Study performed at McMaster University demonstrates significant improvements in oxygen utilization in both sprint interval and endurance training protocols.  Participants performed a 30second sprint, followed by a four minute rest period (4-6 repeats), while the endurance group performed 90-120 minutes of continuous cycling at 65%.  Each protocol resulted in an increased muscle oxidative capacity, while the endurance group committed approximately 8 more hours to training and performed 90% more volume… Knowing how to use your time wisely is critical!   Interval training is also associated with an increased production of growth hormone which plays a critical role in reducing body fat and increasing lean mass.

The workout:

‘A’ Series 3 sets – Heavy sled push

  1. Prowler push 15Yards
  2. BB Thruster x8-12
  3. Pull-ups x 8-12
  4. 30 seconds recovery between exercise, 2 min recovery after each set, 4 minute recovery before beginning B series

‘B’ Series 2 sets – drop weight off sled

  1. Prowler push 30Yards
  2. Sled row x 15-20
  3. Push-ups x 12-20
  4. 30 seconds recovery between exercises, 2 min recovery after each set, 4 minutes recovery before beginning C series

C series 1 set – drop weight off sled

  1. Prowler push 50Yards
  2. Russian twist x20/side
  3. Front plank x45 seconds

Key points:

  • Interval training can be an efficient method to tackle fat loss while preserving or even increasing lean mass
  • Lose fat, increase muscle and improve aerobic fitness simultaneously with interval training
  • Earn your rest with high intensity shorter duration exercise
  • I am not saying to quit jogging, it can serve a purpose, but understand when its appropriate

References, effects of single bout of ver high-intensity exercise on metabolic health biomarkers in overweight/obese sedentary men, effects of high-intensity interval training on the VO2 response during severe exercise, short-term sprint interval versus traditional endurance training: similar initial adaptations in human skeletal muscle and exercise performance, the time course of the human growth hormone response to a 6 s and 30 s cycle ergometer sprint


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