Why is resistance training as effective as cardio training for weight loss, especially for women?
Interesting question. From my background knowledge and research to date, the statement, whereby "resistance training is as effective as cardio training for fat loss" is only correct in a "time relevant" context.
During an exercise session, cardio training potentially utilizes a higher volume of calories when compared to resistance training. However, when the cardio training session ceases, so too does the calorie burning effect (or soon after depending on EPOC state). Alternatively, resistance training has the potential to gradually and progressively increase muscle mass and therefore increase basal metabolic rate (the calories required by your body to maintain basic operations throughout the day and night). Much like putting a bigger engine in a car, more fuel is needed for daily operation
Therefore, to lose fat relatively quickly (i.e., several weeks) and to a greater initial extent, cardio training is essential for the high calorie consumption. In the long term, however, to keep the fat off and decrease the susceptibility to gain fat, resistance training and an increase in muscle mass is required (not to forget the equally, if not more, important nutritional and lifestyle factors).
So, if the aim is to increase calorie utilization, lose body fat and keep the fat off, incorporate both cardio training and resistance training into your program.
Several points in regards to this:
- On reading an increase in muscle mass, many women automatically cringe and picture the muscle bound women in body building magazines. Remember, those women are professional athletes. They have an incredibly strict training and nutritional regime designed specifically for putting on a high amount of muscle and many are blessed with great genetics.
- Some preliminary research has found that, in regards to resistance training, while men increase in lean body mass more than women, women tend to loose more visceral fat (fat around the body’s organs) than men.*
- Apart form the benefits of long term fat utilization, resistance training increases bone loading, a key component in minimizing bone loss and delaying Osteoporosis, a major concern for many women of all ages.
- A final point, I used the term fat loss rather than weight loss as weight can change depending on muscle mass, fat mass, hydration, last meal intake, etc., and as such, few people (weight competitive athletes and power athletes) desire actual weight loss, many truly desire a decrease in body fat. I hope my presumption was correct. If not, then we have a different ball game, as resistance training can actually increase body weight by increasing lean body mass (even with fat loss).
In terms of addressing some of the current theories in regards to cardio versus weight training controversy, one popular theory is, “One can burn more calories in a good set of squats than in a 45 minute aerobics class.”
I agree that the potential for one person to burn more calories in a good set of squats than in a 45 minute aerobic class or even a 30 minute run does exist, just as one can burn more calories walking than running. The reason is the intensity of the session. Squats can have a very high metabolic demand from both the muscle and neurological demands for energy, and I would expect someone to burn more calories doing four sets to failure with a heavy load than someone in a low intensity aerobic class with little desire and/or experience or a fit individual plodding along at a slow jog, which barely increases his/her heart rate. With this in mind, however, scientific research that transcends to the general population when considered in relative terms finds most cardio-based training sessions to have a higher calorie utilization and MET ratio than recreational weight training (see references below).
Interestingly enough, I tried to compare the effects of resistance training to aerobic classes and running with a colleague in 2000. We measured heart rates during and for the first 60 minutes following weight training sessions, aerobic classes and treadmill and road running training sessions.
For the resistance training sessions, we would perform three sets of eight to 10 RM of a lower limb lifting (Deadlift, Squat or Lunge), upper body pushing (Bench Press, Loaded Push Ups, Loaded Dips) and upper body pulling exercise (Bent Over Row, Loaded Chin Ups, Neutral Grip Lat Pulldown), alternating the lead exercises every session for six weeks.
On average, both of us had heart rates over 200 beats per minute when performing the Deadlifts and Squats, which would drop back down to around 120-140 bpm during the two-minute recovery, The lowest heart rates were for the Bench Press (138-148 bpm) with resting heart rates dropping down to 104-112 bpm (when this exercise was performed first). These sessions were literally "throw up sessions" where we went for maximal effort. Heart rates were generally back to resting levels within 20 minutes but would be higher than usual when performing sedentary activities like walking up/down the office stairs. Both of us had similar results when running on the road or treadmill for 30 minutes flat out (the average weight training session went for 28 minutes). We maintained average heart rates of between 158 and 170 beats per minute, and our heart rates dropped to the pre session limit usually after an hour (sometimes not). In the aerobic classes, we differed the most. My partner participated in classes at a local gymnasium, whereas I instructed at the gymnasium where we worked. My heart rates average 155-162 beats per minute during my energy burner classes whereas my partner's heart rates averaged 120-158 beats per minute.
Overall, we calculated that significantly more heart beats were taken from the cardio training sessions than the other two; however, my partner started to show signs of sympathetic nervous system overtraining with the weight training periodization whereas I likewise showed signs of sympathetic nervous system overtraining from the treadmill/road running.
In regards to heart rates and expected calorie utilization (through which there is a linear relationship) during the session and as part of EPOC, the running activities were a clear favorite. However, we had no blood or gas analysis measures, so critical factors like metabolic/hormonal status, the true number of calories utilized, what fuel source provided the energy, etc., were never determined. Using the above example, aerobic exercise classes for me would be expected to achieve substantial calorie utilization but not for my partner. We both agreed that the neurological demands were higher for my partner during resistance training than they were for me (his relative load for both exercises was higher than mine). Conversely, I placed more demands on my neural system when running (my speed was approximately 1.3km/h faster).
In terms of clinical efficacy, over the last 10 years as a Physical Training Instructor for the Australian Armed Forces, training soldiers who range from elite athletes to desk bound sedentary soldiers to those recovering from all manor of injury and surgery, I can attest to the need for an individualized formula for any client goal, including fat loss. With this in mind, I have found the greatest potential for fat loss and maintained fat loss to be in those who perform both anaerobic/aerobic conditioning and resistance training. It is the subtleties of the exercise prescription and training dose that varies.
General Point: The ability and desire of the average individual to perform high neurometabolic resistance training exercises, which require near maximal efforts with substantial loads for an extended training period (i.e., months to years), is questionable.
- Arciero, P.J., & Poehlman, E.T. (2005) Influence Of Exercise And Diet On Metabolic Rate, Sportscience (Draft).
- Howley, E.T., & Franks, B.D., (1997). Health Fitness Instructor's Handbook 2nd Edition. Champaign, IL: Human Kinetics.
- Morgan, B., Woodruff S.J., & Tiidus, P.M. (2003) Aerobic energy expenditure during recreational weight training in females and males, Journal of Sports Science and Medicine, (2), 117-122.
- Phillips W.T. and Ziuraitis, J.R. (2003) Energy cost of the ACSM single-set resistance training protocol. Journal of Strength and Conditioning Research 17, 350-355.
- Wilmore, J.H.,& Costill, D.L., (2004) Physiology of Sport and Exercise.3rd Edition Champaign, IL: Human Kinetics
* Regarding the question of women versus men:
The study by Morgan, Woodruff and Tiidus (2003) did find that women consumed more aerobic energy than men during weight training. My concern with mentioning this study is that, like the fuel source and exercise intensity research, it can easily be taken out of context and people will think that this means women will burn more fat during weight training than men when this is NOT what the study found. The study found women consumed more AEROBIC energy than men. There is no comparison of hormonal/metabolic gender difference influences that will impact on LBM, fat mass and BMR or time dependent factors (i.e., men put on LBM through resistance training to a higher degree than women, increasing BMR to a greater degree). There is a question over whether the men utilized a more anaerobic profile, which will likewise be indicative of calorie utilization and EPOC, and finally, the authors themselves have no explanation as to why this result was found. While promising, the experiment size was very small (eight men and seven women) and was a non-blinded study, so more research is definitely needed in order to draw conclusions one way or another.