ONLINE DRIVERS MEDIA

In general, you have to count and limit your weekly HIIT sessions. Doing as much as humanly possible, could yet make sense, when youre preparing for Olympia 2016 and realize 5 weeks before the event that you have been lingering for too long ;-)

I think as a SuppVersity reader you know by now that "more wont yield more" - no matter if we are talking about supplements or exercise. Now, while weve had countless examples of the "more aint more" principle thats also at the heart of the "Three Simple Rules of Supplementation" (read article) for supplements (e.g. zinc, chromium, etc.) and the simple notion that eating less wont always result in greater weight loss, evidence for the pro-anabolic / adaptive effects of exercise in general, and non-steady state cardio, in particular is scarce. Against that background its all the more important for us to cherish the publication of a paper from the Norwegian University of Science and Technology and the St Olav University Hospital in Trondheim Norway, Roy told me about by messaging me via the SuppVersity Facebook Page.

"More HIIT doesnt help more, either"

I guess the above would be the elevator pitch for the mythical "turbo lift" in Star Trek. For someone like yourself who has learned never to swallow "expert" wisdom just like that, the statement "more HIIT doesnt hep more, either" obviously wont be satisfying.

Figure 2: Illustration of the training in the low frequency (LF) and high frequency (HF) group.

If you look at the illustration above, you will already know somewhat more about the "more" in the previous sentence. As you can see, the parameter that has been modified is not the volume, its the frequency!  - and thus one of the parameters of which many gymrats think that it could hardly be high enough (AM + PM training, 7 days a week - does that ring a bell?). What this people ignore is the simple truth that ...

... adapatation takes time and training more often does not accelerate this process!

In the end, I am actually quite surprised to see that the net VO2 "gain" the scientists measured in the subsequent detraining phase (see Figure 2) was identical. Or, more explicitly, that packing 24 training sessions into three weeks did not blunt the mitochondrial adaptation processes that are responsible for the increase in VO2max, altogether.

Figure 2: VO2max and heart rate values of the 16 healthy subjects before / after high vs. low frequency HIIT (Hatle. 2014)

If we are brutally honest, though, there is obviously an advantage for the 24 sessions in 8 weeks version of this training protocol (see Figure 3, as well). The VO2max scores were after all identical only in the "catch-up" up period in week 11 and due to the rapid decline after week 12 the benefits faded equally rapid in both groups when the 19 healthy, normalweight, but non-athletic subjects returned to their usual laziness (detraining = not training at all).
References:

• Hatle H, Støbakk PK, Mølmen HE, Brønstad E, Tjønna AE, et al. "Effect of 24 Sessions of High-Intensity Aerobic Interval Training Carried out at Either High or Moderate Frequency, a Randomized Trial." PLoS ONE 9(2). (2014): e88375. doi:10.1371/journal.pone.0088375

Bad news for lone wolfs.

Dont we all know this? There are those days when you hit the gym, go through your workout routinely, go home and tell yourself: "Well, Ive done the best I could, I will try to increase the weight next week!" ... I see, you know what I am talking about ;-)

Just like the subjects in a recent study from the University of California Los Angeles, I suppose. All of them were member of the Exquinox Fitness Club, 30–44 years of age, and had a history of exercising 5–7 days per month at the club over the previous 3 month - archetypical average ambitious Gymrats, so to say.
After randomly selecting 40 men who met the above criteria, Thomas W. Storer and colleagues randomly assigned the subjects to either

• a nonlinear periodized training program (TRAINED, N=17), or to 
• a self-directed training (SELF, N= 17)

The total training volume and frequency, i.e. three training sessions per week, was identical for both groups. The same goes for the food intake which was not recorded in either of the groups (unquestionably a drawback).
"The templates for the supervised training regimen were developed by senior EFC staff and guidance

from outside experts including exercise physiologists, physical therapists, certified PTrs, and athletic trainers.[...] The training regimen consisted of a 3-cycle, nonlinear program in which acute program variables including exercise selection, volume, and intensity were varied over both the 4-week mesocycles and within the weekly microcycles."

The volume or intensities of each training session were categorized as high (H), moderate (M), or low (L) and applied on a given day during the course of each week of training. Thats in stark contrast to the SELF group, the members of which had to log their workouts, but were otherwise totally free to train whatever they thought fit for the compulsory training goal "maximize lean mass!"

Figure 1: Changes in weight, lean body and fat mass, as well as body fat % (left) and corresponding rel. (%) changes in chest press, leg press, leg peak and average power (Storer. 2014)

If you take a look at the data in Figure 1 its plain to see that "what you see fit", is not exactly the way of training that worked for the average Joes in the study at hand.
Whats interesting, though, is the fact that all of them made progress - at first that sounds great, but without the comparison to the TRAINED group the guys would never have realized that they could have reduced their body fat % twice as much in the same 12 weeks, if they had had a trainer to plan their routines and kick their asses.

Figure 2: The lean body mass (LBM) gains in the self-directed training group did not gain any muscle on average. One guy even lost ~4kg of lean mass in 12 weeks - in spite of being told to train for maximal hypertrophy (Storer. 2014)

If you take a closer look at the data in Figure 2 you will also see that for some, the self-selected training regimen - although designed to deliver maximal muscle growth - led to significant decreases in lean muscle mass - in one of the subjects almost 4kg of lean muscle mass in 12 weeks in the course of which he was told to "maximize muscle growth".

Although I can only speculate about the reason for his misery, I suspect he was overtraining. Doing more instead of less, when the gains he was expecting as a reward didnt come.
References:

• Storer, Thomas W.; Dolezal, Brett A.; Berenc, Matthew N.; Timmins, John E.; Cooper, Christopher B. "Effect of Supervised, Periodized Exercise Training vs. Self-Directed Training on Lean Body Mass and Other Fitness Variables in Health Club Members." Journal of Strength and Conditioning Research (2014). Ahead of Print.

Compared to liquid beverages, gels have the advantage of causing lower GI stress, when significant quantities of CHOs are consumed during exercise. Bars, can be held in the cheek pouch and chewed during critical phases of a race.

The headline gives it away. Todays SuppVersity article is a brief review of the (mostly sponsored) literature on Gatora.... ah, I mean carbohydrate supplementation during exercise. The headline also implies that the usefulness and efficacy of carbohydrate supplements depends on exercise duration and the type of exercise.

As a seasoned student of the SuppVersity you will know that certain paradox involved with regard to the duration / type of exercise. Short exercise durations, for example, shouldnt require large CHO boluses, long duration exercise, on the other hand, is fueled mostly by fat - so why should you supplement with carbohydrates, anyway?
I promise to answer this and other questions in the following paragraphs, but before I do so, I would like to point out that there is as of now no evidence that the much-praised "fat adaptation" increases the exercise performance to an "Olympia" level. Carbohydrate supplements, on the other hand, are still part of the regular supplementation regimen for the 99% of the top athletes.

That being said, the human physiology dictates that the use of carbohydrate supplements during aerobic workouts that last less than 60 minutes is useless, because muscle glycogen is generally not limiting to performance when exercise durations are less than ~60 minutes.

It should not work for short duration exercise, but it still does

Interestingly, 16 out of 23 studies, Trent Stellingwerff and Gregory R. Cox from the Canadian Sport Institute-Pacific and the Australian Institute of Sport reviewed for their recent paper in Applied Physiology have found that carbohydrate supplementation and/or oral (mouth) exposure to carbohydrate can improve performance of tasks less than 1 hour in duration:

You wont fully deplete your muscular glyocogen levels during short duration resistance training (Haff. 2003)

"In 2004 a seminal paper was published showing that a carbohydrate mouth-wash (swirling 25ml of a 6% CHO beverage (only ~1.5g of CHO in 25ml [6.4% maltodextrin solution (CHO)]) around in the mouth for ~10 sec, every 7.5min) significantly improved time trial (TT) performance [in seven male and two female endurance cyclists] by ~3% (Carter et al. 2004a)." (Stellingwerff & Cox. 2014)

This effect of CHO mouth-washing to improve performance in events from 30-60min has now been replicated in several other performance studies (10 of 13 studies) using both cycling and running interventions and with both sweet (sucrose) and non-sweet (maltodextrin) caloric CHO sources,as compared to 5 non-caloric artificial sweetener placebo trials showing no performance enhancing effects.

Figure 1: Hard to believe, but true - In 2010 Pottier et al. observed that CHO mouth-rinsing, but not CHO ingestion increases the 1h high intensity time-trial performance in trained subjects.

 "All these findings have been mechanistically supported with a functional magnetic resonance brain imaging study showing that CHO mouth-washing from both sweet tasting glucose and non-sweet maltodextrin can stimulate the brain areas of the insula/frontal operculum, orbitofrontal cortex and striatum, which are involved with brain centers responsible for reward and motor control (Chambers et al. 2009). Interestingly, if the mouth (oral receptors) and GI tract is by-passed by CHO infusion straight into the blood stream then 1h cycling TT performance was unaltered as compared to no CHO supplementation (Carter et al. 2004b)." (Stellingwerff & Cox. 2014)

Studies evaluating the effects on perceived exertion (Fares et al. 2011) found similar benefits all of which support the idea that the effect does not occur in the musculature, but rather in the head.
It should be obvious that the physiological, or rater intra-muscular benefits of carbohydrate supplements increases with the exercise duration.

CHO supplementation during exercise that lasts 60 minutes or longer

In view of the fact that it is 100% logical and well established by studies by Coyle et al. (Coyle 1992a; Coyle 1992b) that the intake of carbohydrate (glucose alone, and glucose + fructose blends) can significantly improve prolonged endurance capacity and performance (>60min of exercise (Jeukendrup 2010)).

Figure 2: Overview of the performance increases in the 50 studies Stellingwerff & Cox reviewed (2014)

Against that background I will not bother you with another overview of the results, but focus on the efficacy of different carbohydrate supplementation strategies and types of carbohydrate supplements for exercise durations beyond the "magical" hour.

Glucose + fructose - the combination advantage

As a SuppVersity reader youve previously heard about the benefits of combining glucose and fructose in your intra-workout beverage. It is thus only logical that most commercially available formulas are mixtures  glucose + fructose (GLU:FRU) or maltodextrin + fructose - so-called "multi-transportable CHOs". The advantage of using both glucose and fructose is that the carbohydrates will be absorbed via SGLT1 and GLUT5 intestinal transporters.

Specifically during long(er) duration exercise, when the carbohydrate consumption can exceed 60g/h there is a significant performance increase with multi- vs. single source carbohydrate supplements (Stellingwerff & Cox. 2014)

An advantage that has been scientifically established among others by Jeukendrup et al. (2010) who found that this pattern of CHO ingestion results in ~20 to 50% higher CHO oxidation rates compared to the ingestion of a drink that contains nothing but glucose or maltodextrin.


Now an increase in carbohydrate oxidation alone does not sound like something you would aim for as an endurance athlete. In practice, increases in carbohydrate oxidation have yet been shown to increase the performance during prolonged exercise bouts compared to isocaloric glucose-only beverages. (Currell et al. 2008; Triplett et al. 2010; OBrien et al. 2011; OBrien et al. 2013).
Needless to say that there is still research to be done with respect to individual influencing variables of carbohydrate requirements. The currently available evidence, for example, is largely based on results from runners and cyclists. Two other factors / issues that come to mind are...

• the dose-response relationship, which appears to be capped at 75g/h - at least according to a large-scale multi-center study by Smith et al. (Smith. 2013) who found that their subjects, endurance trained cyclists or triathletes experienced significant performance increases, with increasing amounts of carbohydrates (0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110 and 120g of CHO/h) during a 2h constant load ride.
  
  

  Figure 3: Mean log time to complete time trial (natural) as function of CHO treatment condition with fitted quadratic curve (with 95% CI of mean curves). Differences 100 represent percent change in performance. The quadratic function relating CHO ingestion rate to time complete time trial for 43% (95% CI = 11%–75%,P= 0.059) of the variation in mean performance score (Smith. 2013)

  The CHO given was a 1:1:1 glucose:maltodextrin:fructose blend. Results indicated incremental performance improvements of 1.0%, 2.0%, 3.0%, 4.0%, and 4.7% at 9, 19, 31, 48, and 78g CHO/h, respectively, with diminishing performance enhancement seen at CHO levels >78g/h.
  
  The optimal amount for performance (+4.7%) was 78g/h, with a range of 68 to 88g/h. However, even at 10g/h, a 1.0% increase in performance was observed, showing even a small amount of carbohydrate has the potential to positively impact performance. 
• the optimal mix of glucose, dextrose, fructose, maltodextrin or other "special" carbohydrates  - needless to say that waxy maize, hydroxypropyl distarches (learn more) or the expensive fast absorbing highly insulinogenic patented carbohydrate source Vitargo come to mind, when we are talking about finding the optimal mix of different carbohydrate sources - a mix, by the way, of which you can safely assume that it will differ according to the physiological demands of the workout and the exercise duration.
  
  One thing we shouldnt forget, though, is that next to optimal performance, optimal GI tolerance, i.e. the absence of bloating, diarrhea & co would be an important criteria the "optimal" carbohydrate blend would have to meet.

• Figure 4: CHO suppl. ameliorates  testosterone reductions in 800m runners (de Sousa. 2010)

  the impact of carbohydrate supplementation on hormonal changes during and in response exercise - several human studies suggest that CHO supplementation attenuates the suppression of the hypothalamic-pituitary-gonadal axis and the rise in stress hormones during periods of intense training; a recent rodent study shows that the provision of carbohydrate supple- ments can prevent / reverse exercise-associated menstrual dysfunction (de Sousa. 2010; Zhao. 2014)

I guess, I could come up with additional research gabs, but in the end, a list of "gaps" is not exactly useful for you. Much in contrast to a conclusion, which I am about to formulate in the bottom line, now.
References:

• Carter,  J.,  Jeukendrup,  A.E.,  Mundel,  T.,  and  Jones,  D.A.  (2003).  Carbohydrate  supplementation  improves moderate and high-intensity exercise in the heat. Pflügers Archiv : European journal of physiology446: 211-9.
• Carter, J.M., Jeukendrup, A.E., and Jones, D.A. (2004a). The effect of carbohydrate mouth rinse on 1-h cycle time trial performance. Medicine and science in sports and exercise36: 2107-11.
• Carter, J.M., Jeukendrup, A.E.,  Mann, C.H., and  Jones, D.A. (2004b). The effect of glucose infusion on glucose kinetics during a 1-h time trial. Medicine and science in sports and exercise36: 1543-50. 
• Chambers,  E.S.,  Bridge,  M.W.,  and  Jones,  D.A.  (2009). Carbohydrate  sensing  in  the  human  mouth:  effects  on exercise performance and brain activity. The Journal of physiology587: 1779-94. 
• de Sousa, Maysa Vieira, et al. (2010). Effects of carbohydrate supplementation on competitive runners undergoing overload training followed by a session of intermittent exercise." European journal of applied physiology 109.3: 507-516.
• Fares, E.J. and Kayser, B. (2011). Carbohydrate mouthrinse effects on exercise capacity in pre- and postprandial States. J Nutr Metab2011: 385962.   
• Pottier, Andries, et al. (2010). Mouth rinse but not ingestion of a carbohydrate solution improves 1?h cycle time trial performance" Scandinavian journal of medicine & science in sports 20.1: 105-111.
• Sawka,  M.N.,  Burke,  L.M.,  Eichner,  E.R.,  Maughan,  R.J.,  Montain,  S.J.,  and  Stachenfeld,  N.S. (2007).  American College of Sports Medicine position stand. Exerciseand fluid replacement. Medicine and science in sports and exercise39: 377-90.
• Smith, JohnEric W., et al. (2013). Curvilinear dose-response relationship of carbohydrate (0-120 g/h) and performance." Med Sci Sports Exerc 45.2: 336-341. 
• Stellingwerff, T., & Cox, G. R. (2014). Systematic Review: Carbohydrate Supplementation on Exercise Performance or Capacity of Varying Durations. Applied Physiology, Nutrition, and Metabolism (2014). Ahead of Print. 
• Zhao, Can, et al. (2014). Effects of carbohydrate supplements on exercise-induced menstrual dysfunction and ovarian subcellular structural changes in rats." Journal of Sport and Health Science 3.3: 189-195.