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Bench press bros, listen up! You better push that weigh up fast, if you want to make maximal strength gains - O-lifting says "Hello" ;-)

Do you train deliberately slow? If so, you may be limiting your strength gains. A recently published paper in the European Journal of Sports Science shows: "Movement velocity can be considered a fundamental component of RT intensity, since, for a given %1RM, the velocity at which loads are lifted largely determines the resulting training effect" (Gonzalez-Badillo. 2014).

Before we take a closer look at how "large" the effect of training the training velocity actually is, I would like to invite you to take a closer look at the design of the corresponding experiment that was conducted at the Pablo de Olivade University in Seville, Spain.
The experiment was designed in an attempt to clarify the influence of repetition velocity on the gains in strength consequent to isoinertial resistance training. To this ends, the scientists conducted two separate studies:

• Study I compared the effect of two distinct RT interventions on strength gains using movement velocity as the independent variable. Two groups that only differed in actual repetition velocity (and consequently in time under tension, TUT): maximal intended velocity (MaxV) vs. half-maximal velocity (HalfV) trained three times per week for 6 weeks using the bench press (BP) exercise, while the remaining programme variables (number of sets and repetitions, inter-set rests and loading magnitude) were kept identical.
• Study II was a complementary study that aimed to analyze whether the acute metabolic (blood lactate and ammonia) and mechanical response (velocity loss) was different between the type of MaxV and HalfV protocols previously used in Study I

Of the 24 men who volunteered to participate in Study I, only 20 successfully completed the entire study (mean ± s: age 21.9 ± 2.9 years, height 1.77 ± 0.08 m, body mass 70.9 ± 8.0 kg). Therefore, the scientists recruited 10 additional participants (25.3 ± 3.4 years, 1.77 ± 0.08 m, body mass 75.2 ± 8.7 kg) for the follow up study (Study II).
The participants were physically active sport science students with 2–4 years of recreational RT experience in the bench press exercise - a fact that may be important if you take into consideration what I wrote about the Pereira study in the red box above.

Figure 1: Schematic timeline of study design (Gonzales-Badillo. 2014)

"Based upon pre-test 1RM strength performance, participants were allocated to one of the two groups following an ABBA counterbalancing sequence: MaxV (n = 9) or HalfV (n = 11) [the non-random allocation to the two groups ensured that there was no significant strength difference between the two groups at the beginning of the study].

The only difference in the RT programme between groups was the actual velocity at which loads were lifted: maximal intended concentric velocity for MaxV vs. an intentional half-maximal concentric velocity for HalfV [note the difference between doing each rep at maximal velocity and trying to do so!]."

Both groups trained three times per week, on non-consecutive days, for a period of 6 weeks using doing nothing but bench presses on each of the workout days. In that, Study I and II were performed 3 weeks apart using a different sample of participant.

Figure 2: Changes in bench press 1-RM over the course of Study I. The relative changes are 16% increase in the maximal 9% increase in the 50% velocity group (Gonzales-Badillo. 2014)

As you can see in Figure 2 the scientists are right, when they say that it seems as if "[m]ovement velocity can be considered a fundamental component of RT intensity, since, for a given %1RM, the velocity at which loads are lifted largely determines the resulting training effect" (Gonzalez-Badillo. 2014). A corresponding difference in lactate production during the workouts was yet detected only if the exercise was performed at low intensities and high speed, i.e. 3 × 8 with 0.79 m/s at ?60% of the 1RM and with 3 × 6 with 0.62 m/s a ?70% of the 1RM.
References:

• González-Badillo, Juan José, et al. "Maximal intended velocity training induces greater gains in bench press performance than deliberately slower half-velocity training." European journal of sport science ahead-of-print (2014): 1-10.
• Ingebrigtsen, Jørgen, Andreas Holtermann, and Karin Roeleveld. "Effects of load and contraction velocity during three-week biceps curls training on isometric and isokinetic performance." The Journal of Strength & Conditioning Research 23.6 (2009): 1670-1676.
• Pareja-Blanco, F., et al. "Effect of Movement Velocity during Resistance Training on Neuromuscular Performance." International Journal of Sports Medicine EFirst (2014).
• Pereira, Marta Inez Rodrigues, and Paulo Sergio Chagas Gomes. "Effects of isotonic resistance training at two movement velocities on strength gains." Revista Brasileira de Medicina do Esporte 13.2 (2007): 91-96.
• Sakamoto, Akihiro, and Peter James Sinclair. "Muscle activations under varying lifting speeds and intensities during bench press." European journal of applied physiology 112.3 (2012): 1015-1025.

Remember: HIIT does not have to happen on the treadmill.

If you havent already done so, I suppose you are currently revising last years training regimen: Reviewing what worked and what didnt work; and thinking about (new) goals and the best ways to achieve them.

If you havent yet decided on what type of cardio training you want to do, todays SuppVersity article may help you make the right endurance / cardiovascular exercise choices for 2015. In that, the headline already revealed: At least 50% of your 2015 "Cardio" training should be high intensity interval training (HIIT) - and here is why.

1. HIIT is more time efficient - Unless you have lost your hob and are looking to kill the newly won time in 2015, you are probably similarly short on time as most of us. Against that background, the mere time efficiency of HIIT workouts are an argument even the most feverish advocates of  low-intensity hour-long cardio cannot deny (Gaesser. 2011; Gillen. 2013).
   

   Figure 1: In contrast to often-heard claims, HIIT is not just a "glucose burner" its also a fat burner. It does (a) increase the oxidation of fatty acids after the workout and (b) increases your muscles and other cells general ability to oxidize fat as fuel (see figure from Talanian. 2007).

   "As few as 6 sessions of HIIT over a 2-week period for a total of about 15 minutes of very intense exercise (equating to approximately 600 kJ or 143 cal) have been shown to increase skeletal muscle oxidative capacity and alter metabolic control during aerobic-based exercise (Gibala. 2008). And 7 HIIT sesssions performed over 2 weeks significantly heightened whole body and skeletal muscle capacity for fatty acid oxidation during exercise in moderately active women (Talanian. 2007). For those who have limited time to work out, this makes HIIT an intriguing option" (Schoenfeld. 2009).

   And even if your goal is not to get fitter, but rather to burn more energy, HIIT can do what steady state cardio will never achieve, i.e. burn 14.5 kcal/min (see "Tabata Workouts: Do They Work & How Energy-Demanding Are They? 14.5 Kcal/Min Sounds Nice, But You Must Earn It!" | learn more). In the end, short workouts will thus increase your 24h energy expenditure to the same extend endless steady-state workouts would do (Skelly. 2014).
   

   "HIIT may help insufficiently active individuals overcome a major barrier to maintaining a physically active lifestyle, that of a perceived lack of time. An added bonus is that from a time:benefit perspective, HIIT may prove to be a good example where less can be more" (Gaesser. 2011).

   And it does not even take a Tabata workout to time-efficiently improve your health. As a SuppVersity reader you will be aware that "4x4 Minutes of HIIT Per Week Thats All It Takes For Already Well-Conditioned Individuals to Stimulate Mitochondrial Growth ? 15% Increase in VO2Max, Peak & Mean Power" | learn more.
2. HIIT has more favorable effects on your glucose metabolism and heart health - You probably have heard that 1h on the treadmill was the ideal exercise for the obese type II diabetic, right? Well, this may in fact be true, but the reason thats ideal for an obese type II diabetic is that even walking on a treadmill is a high intensity exercise for someone who weighs 300-450lbs.
   

   Figure 2: A 2008 study in healthy, normal-weight young women proves: HIIT "cardio" training leads to significantly more pronounced improvements in all three central variables of glucose metabolism than a comparable steady-state "cardio" workout (Trapp. 2008).

   That being said, for all of you with at least a decent amount of fitness, HIIT training with its ability to burn tons of glycogen within just a few minutes should be the preferred mode of exercise. A mode of exercise which has far more potent effects on the expression of the anti-diabetic, anti-obesity and anti-metabolic syndrome proteins AMPK and SIRT-1 than any other form of exercise (Gurd. 2010) and has thus not surprisingly been shown to have superior effects on central markers of glucose metabolism in a 2008 study by Trapp et al. - and that in healthy, lean, young women (see Figure 2).
   
   A similar superiority has been observed by Weston et al. (2013) in patients with lifestyle-induced cardiometabolic disease. Their systematic review and meta-analysis in the British Journal of Sports Medicine indicates that "HIIT significantly increases CRF [cardio-respiratory fitness] by almost double that of MICT in patients with lifestyle-induced chronic diseases." (Weston. 2013).
3. HIIT exercise will help curb your cravings - While steady-state "cardio" has repeatedly been associated with increases in appetite, hunger and most importantly food intake, there is good evidence that "Intensity [is] the Key to Minimize Exercise Induced Cravings?" (learn more)
   

   Figure 3: Effects of exercise duration and intensity on energy intake; exemplary study results from Erdmann et al. (2007, left) and Larson-Meyer et al. (2012, right).

   I dont want to repeat myself on this one. Instead I will just refer you to a recent SuppVersity article on that matter and the plethora of evidence that confirms the negligible or beneficial effects of high intensity interval training on appetite, hunger and how much food you eat and thus ruin any exercise-induced reduction in your daily energy balance (Alkahtani. 2014; Martins. 2014).
   
   

   Figure 4: VAS scores for hunger (A), desire to eat (B), fullness (C), and thirst (D) during REST (black line) and EX (gray line) (n = 15). Hatched rectangles represent the treadmill run/rest; striped rectangles represent the fMRI scan (Crabtree. 2014).

   Before I go on to the #4 on the benefits list, I would yet like to highlight the following result from a recent study from the University college of London:
   

   "Exercise increases neural responses in reward-related regions of the brain in response to images of low-calorie foods and suppresses activation during the viewing of high-calorie foods" (Crabtree. 2014)

   Cant believe what you just read? Look at the figure on the right which depicts the VAS scores for hunger, desire to eat, fullness, and thirst, during REST (black line) and EX (gray line) in N=15 lean healthy men who completed two 60-min trials—exercise and a resting control trial (REST).
   
   Thus, the study clearly confirms the validity of the suggestion to stay scrap your steady-state cardio workouts and replace them with HIIT, in order to finally be able to stick to your diet plans and see the fat loss you are looking for.
4. HIIT ramps up the metabolism instead of ruining it - As long as you dont overdo it by training too often or extending your HIIT sessions to 1h, HIIT will produce a profound "after burn" thats 3x higher than in the case of classic steady-state "cardio" workouts.
   

   Figure 5: EPOC and corresponding additional energy expenditure in the high intensity 3x Wingate group (SPIE) and the 30min continuous exercise group (HIE) during the 30 min right after the workout (Townsend. 2013)

   As a standalone, this previously reported benefit is hardly worth the paper it is printed on. In conjunction with the previously mentioned benefits, however, it is an important benefit of HIIT that must not be underestimated.
5. HIIT is perfectly scalable - Unlike steady-state cardio, where you would have to endlessly increase your workout times, HIIT workouts are easily scalable. You can either...
   

   • HRV = heart rate recovery analyses are a great tool to monitor your training & recovery | learn more

     do an additional interval (volume increase),
      
   • increase the resistance on your training device or run / cycle on a more difficult track (intensity increase),
   • increase the speed at which you run, pedal or row (intensity increase), or
      
   • reduce the time of active rest between the intervals (intensity increase)
   and thus have many more options to tweak the workouts to your individuals needs. For beginners this is not that important. An obese type II diabetic has plenty of room to increase the pace and / or duration of his / her steady-state "cardio" workouts. A trained athletes, on the other hand, will soon hit a wall, when he / she begins to cycle at 90% intensity for 2h everyday.

References:

• Alkahtani, Shaea A., et al. "Acute interval exercise intensity does not affect appetite and nutrient preferences in overweight and obese males." Asia Pacific journal of clinical nutrition 23.2 (2014): 232.
• Crabtree, Daniel R., et al. "The effects of high-intensity exercise on neural responses to images of food." The American journal of clinical nutrition 99.2 (2014): 258-267.
• Erdmann, Johannes, et al. "Plasma ghrelin levels during exercise—effects of intensity and duration." Regulatory peptides 143.1 (2007): 127-135.
• Gaesser, Glenn A., and Siddhartha S. Angadi. "High-intensity interval training for health and fitness: can less be more?." Journal of Applied Physiology 111.6 (2011): 1540-1541.
• Gibala, Martin J., and Sean L. McGee. "Metabolic adaptations to short-term high-intensity interval training: a little pain for a lot of gain?." Exercise and sport sciences reviews 36.2 (2008): 58-63.
• Gillen, Jenna B., and Martin J. Gibala. "Is high-intensity interval training a time-efficient exercise strategy to improve health and fitness?." Applied Physiology, Nutrition, and Metabolism 39.3 (2013): 409-412.
• Gurd, Brendon J., et al. "High-intensity interval training increases SIRT1 activity in human skeletal muscle." Applied Physiology, Nutrition, and Metabolism 35.3 (2010): 350-357. 
• Larson-Meyer, D. Enette, et al. "Influence of running and walking on hormonal regulators of appetite in women." Journal of obesity 2012 (2012).
• Martins, Catia, et al. "Effect of Moderate-and High-Intensity Acute Exercise on Appetite in Obese Individuals." Medicine and science in sports and exercise (2014). 
• Owens, Krystyna. "The effectiveness of high intensity interval training in improving VO< sub> 2</sub> max for performance gains as compared to standard endurance training in athletes." (2013).
• Schoenfeld, Brad, and Jay Dawes. "High-intensity interval training: Applications for general fitness training." Strength & Conditioning Journal 31.6 (2009): 44-46. 
• Skelly, Lauren E., et al. "High-intensity interval exercise induces 24-h energy expenditure similar to traditional endurance exercise despite reduced time commitment." Applied Physiology, Nutrition, and Metabolism 39.999 (2014): 1-4.
• Talanian, Jason L., et al. "Two weeks of high-intensity aerobic interval training increases the capacity for fat oxidation during exercise in women." Journal of applied physiology 102.4 (2007): 1439-1447. 
• Townsend JR, Stout JR, Morton AB, Jajtner AR, Gonzalez AM, Wells AJ, Mangine GT, McCormack, WP Emerson NS, Robinson EH, Hoffman JR, Fragala MS Cosio-Lima L. Excess Post-Exercise Oxygen Consumption (EPOC) Following Multiple Effort Sprint And Moderate Aerobic Exercise. Kinesiology. 2013; 45(1):16-21
• Trapp, E. G., et al. "The effects of high-intensity intermittent exercise training on fat loss and fasting insulin levels of young women." International journal of obesity 32.4 (2008): 684-691. 
• Weston, Kassia S., Ulrik Wisløff, and Jeff S. Coombes. "High-intensity interval training in patients with lifestyle-induced cardiometabolic disease: a systematic review and meta-analysis." British journal of sports medicine (2013): bjsports-2013.

Shouldnt it be obvious that the "happy medium" must be the solution, when high protein leads to brittle bones, and low protein to frail muscle? Sure! But where is this "happy medium"?

Some of you may remember my recent Facebook post "High Protein Diet in the Firing Line. Rodent Study Says: Kidneys Are at Risk". It was based on a press release you could read on all the major science-news outlets on the Internet; a press release that will give the average reader the impression that the corresponding study by Aparicio et al. would "prove" that high protein diets will ruin your kidneys and eventually jeopardize your health (read more).

Another paper (Cao. 2014), Jose Antonio, the CEO of the ISSN and the editor of the ISSNs journal posted on Facebook yesterday, didnt get as much media attention, though.

No wonder, the message of this study is after all not in line with one of the fundamental arguments you will hear, whenever you question the allegedly necessary restriction of total protein intake to 0.8g/kg, maximally 1.2g/kg protein per kilogram body weight day in the current nutritional guidelines:

"[...S]hort-term consumption of high-protein diets does not disrupt calcium homeostasis and is not detrimental to skeletal integrity."

Thats not what you will learn at med-school and it is certainly not in line with the hysteria about protein intakes that are 2x or even 3x higher than the 0.8g protein per kilogram body weight we are supposed to consume. Apropos RDA, the subjects in the control group of the said study by Jay J Cao et al. consumed a diet that contained exactly those 0.8g/kg body weight thats supposed to be good for us. The 21 human guinea pigs in the treatment groups, on the other hand, consumed 2x and 3x more than the average dietitian would recommend and they did so for 31 days (Cao. 2014).

Figure 1: Protein intake (in g/day; left), mineral intake (in mg/day; middle)  and calculated renal acid load (in mEq; right) of 49 normal weight, healthy men (n=32) and women (n=7) who consumed normal (0.8g/day), high (1.6g/kg per day) and very high protein (2.4g/kg per day) energy restricted (40%) diets for 4 weeks (Cao 2014)

If you take a look at the PRAL values in Figure 1, you can see that math (not bio- or physiology!) tells us that this reckless practice could compromises the acid-base balance of the healthy, normal-weight subjects, whose energy restricted diets were modeled on the increasingly popular high protein weight loss diets.

Equations vs. experiments | PRAL vs. urinary calclium loss | theory vs. practive

The urinary analysis the scientists conducted does yet speak a very different language. There is, as the scientists emphasize in the discussion of the results no evidence that

Suppversity Suggested Read: "High protein diet = high protein loss" | more

"habitual consumption of dietary protein at levels above the RDA [would] significantly alter urinary calcium excretion, dietary calcium retention, or markers of bone turnover or BMD, despite increased urinary acidity. These results indicate that diets that are 2 or 3 times the RDA for protein are not detrimental to calcium homeostasis when calcium and vitamin D are consumed at recommended intake"

In that I would like to emphasis the importance of adequate calcium (min. 800mg/day) and vitamin D intakes (800-1000IU/day) and the fallacy of the word "habitual". The study at hand did not test the effects of "habitual" high protein consumption. It tested the effects of short-term (28 days) high protein consumption in a low calorie scenario, which is by definition less prone to produce adverse inflammatory and thus potentially pro-osteoporotic side effects (Mundy. 2007).

Not eating enough protein could increase bone loss, when youre dieting

In view of the fact that the evidence I am about to cite, stems from rodent model of postmenopausal bone metabolism, I deliberately used the word could in the headline of this paragraph. And still, the way in which the low protein diet  "negatively impacted bone mass and magnified the detrimental effects of vitD and/or estrogen deficiencies" (Marotte. 2013) in the pertinent study from the Buenos Aires University is particularly disturbing.
The (postmenopausal) women the scientists try to model with their ovariectomized rats (=rats whose ovaries have been removes) are after all one of the many patient groups who are advised to carefully control their protein intake to make sure that the additional acid load will not compromise their bone health even further and that in spite of the fact that there is ample evidence that the current RDA for protein is inadequate to maintain optimal health, particularly when the total energy intake is restricted and especially in populations who are susceptible to bone loss (Kerstetter. 2005; Chernoff. 2004).

Figure 2: We know for quite some time not that low protein diets decrease the absorp- tion of protein (Kerstteter. 2005). Its not certain if this is "just" a homeastatic me- chanism to stabilize the net/acid balance.

In their 2005 study, Kerstetter et al. were in fact able to show that protein intakes that are 2.6x higher than the RDA increase the effective absorption of calcium from the diet (see Figure 2).

This increase stands in contrast to the significant decrease in calcium absorption the researchers observed in the healthy young (age: 26y) women in the low protein arm (0.7g protein per kg body weight) of the study and should remind us that a reduction in protein intake is not going to stop the insidious loss of bone thats caused by the triage of low estrogen, no exercise and a diet that may be low in protein, but high in acid producing grains (Remer. 1995) and devoid of alkaline fruit and vegetables.

I could now go more into details, but I will just leave you with the notion that the "paleo diet" is, despite its high meat content, among the most kidney-, and above all bone-friendly diets we know. In fact, its fruit and vegetables content yield a net alkaline renal load, and will lead to significant improvements in urinary calcium excretion rates (Appelet. 1997; Frassetto. 2013).   

? Note: If you want more about the "Paleo connection" - let me know this (best on Facebook) and what you would be most interested in and I will address that in a future SuppVersity article.

References

• Aparicio, V. A., et al. "High-protein diets and renal status in rats." Nutrición hospitalaria: Organo oficial de la Sociedad española de nutrición parenteral y enteral 28.1 (2013): 232-237.
• Appel, Lawrence J., et al. "A clinical trial of the effects of dietary patterns on blood pressure." New England Journal of Medicine 336.16 (1997): 1117-1124. 
• Cao, Jay J., et al. "Calcium homeostasis and bone metabolic responses to high-protein diets during energy deficit in healthy young adults: a randomized controlled trial." The American journal of clinical nutrition 99.2 (2014): 400-407.
• Chernoff, Ronni. "Protein and older adults." Journal of the American College of Nutrition 23.sup6 (2004): 627S-630S. 
• Frassetto, L. A., et al. "Established dietary estimates of net acid production do not predict measured net acid excretion in patients with Type 2 diabetes on Paleolithic–Hunter–Gatherer-type diets." European journal of clinical nutrition 67.9 (2013): 899-903.
• Kerstetter, Jane E., et al. "The impact of dietary protein on calcium absorption and kinetic measures of bone turnover in women." Journal of Clinical Endocrinology & Metabolism 90.1 (2005): 26-31.
• Mundy, Gregory R. "Osteoporosis and inflammation." Nutrition reviews 65.s3 (2007): S147-S151.
• Remer, Thomas, and Friedrich Manz. "Potential renal acid load of foods and its influence on urine pH." Journal of the American Dietetic Association 95.7 (1995): 791-797.