Why I No Longer Like Lactate Testing

Why I No Longer Like Lactate Testing

Dr. Phil Maffetone

As both physician and coach, working with an athlete is an ongoing process of intense assessment followed by specific actions. Included are various physical, biochemical, mental, and emotional evaluations that yield essential information vital for follow-up activity.

Follow up actions include treatment of abnormal physical findings, such as muscle imbalance, recommending optimal eating, and creating a training program based on individual needs. Other issues involve regulating stress, mental imagery, and simple biofeedback. Responses to these actions are also assessed, and become part of an ongoing process.

The back-and-forth assessment-action process persists with the continual goal of building fitness and improving performance without sacrificing health. Pushing one’s body while maintaining this delicate balance may be the best way to reach optimal athletic potential.

Testing 1, 2, 3 . . .

When I started working with athletes in 1977, measuring an individual’s many health and fitness features was a priority. My education emphasized this process, and the experience quickly taught me how important it would be in uncovering the cause of an injury and other problems that interfered with athletic progress. In a real sense, a large database of personal information was vital for success.

Evaluations included treadmill and cycling testing in my clinic, and field evaluations on the track, in the pool, and at other locations. From samples of blood, urine, and saliva, more assessments meant additional data to better fine-tune the athlete. Specific tests included lactate, along with hormones, fats, vitamins, minerals, enzymes, red and white blood cells, and many others. In addition, analysis of posture and gait, and biofeedback assessments including muscle testing were important. By measuring oxygen uptake and carbon dioxide output, the percentage of sugar- and fat-burning at specific heart rates could be determined. An ongoing oral health history may have been the most important assessment tool, which is still true today.

This process took considerable time. As the years passed I reduced the use of those tests that gave back less information—especially the ones that told me what other more useful evaluations provided. Low on the list was blood lactate.

Unloading Lactate

Today’s technology allows for easy and accurate measurement of lactate. Traditionally tested from blood, other high tech tests will hit the market soon. For example, a new biosensor in the form of a temporary tattoo is being developed which will measure lactate in sweat.

Lactate is an important part of a healthy metabolism, during both aerobic and anaerobic activity. Far from being a “waste product” or the limiting factor in performance as once thought, this metabolite of muscle lactic acid is always being produced, and serves as an important source of energy for the whole body. But obtaining a lactate level may not be as meaningful as most think.

Training lactate levels do not reflect production from lactic acid in muscles, but rather, its clearance from the blood. This might appear academic, but those who metabolize it quicker have lower levels, while others may maintain higher ones. The ability to break down lactate is a reflection of overall health, in particular that of the liver and kidneys, with the nutritional status being especially important. All these factors can change from day to day, and even within a single day.

Thiamin (vitamin B1) and magnesium are examples of two key substances necessary in sufficient amounts to properly metabolize lactate. Lower levels of these nutrients are associated with higher lactate readings, with the real possibility of misinterpretation and other errors when applying the results to training.

A computerized diet analysis, which I used throughout my career, is still an excellent, easy, and inexpensive way to assess one’s nutrient intake. In large numbers of athletes, thiamin and magnesium (and often other nutrients) does not even reach minimum RDA levels, a reflection of poor eating. In addition to lactate, this will have negative effects on other areas of athletic function as well. (The answer to this problem is not supplementation but improving the overall quality of food consumption.)

Blood lactate is often measured to obtain information about lactate and or anaerobic thresholds (AT) associated with increased exertion, higher heart rate, and changes in energy needs. Inclusion of much more anaerobic, sugar-burning activity becomes necessary at this training level. But there is no single lactate level clearly associated with these thresholds. And, as discussed below, aerobic development, not anaerobic, is a key to endurance success.

Whenever I hear that “T” term it reminds me of the Moody Blues 1969 hit album, “On the Threshold of a Dream”—that’s creative. The lactate and anaerobic thresholds, on the other hand, are almost academic.

No-Zone

While endurance success follows aerobic development, there is still a place for anaerobic training. When doing so, I prefer using the full spectrum of the neuromuscular system—the brain’s stimulation of all the muscle fibers—rather than smaller groups of them associated with a particular heart rate zone. This involves increasing the pace from rest through max aerobic levels to high anaerobic states and back down. This is a “no-zone” approach, and when properly implemented, which includes a significant warm up and cool down, the full-body benefits are boundless.

Endurance racing relies primarily on aerobic metabolism. In fact, 98 to 99 percent or more of an athlete’s energy is generated by the aerobic system during a triathlon or marathon, for example. This being the case, why the popularity of such a focus on finding thresholds of anaerobic lactate levels? It is high risk with low potential return as anaerobic workouts are more commonly associated with injury, reduced health, and overtraining.

Decades ago I learned to focus primarily on developing the aerobic system of endurance athletes. When followed strictly, the results were better performance, increased physical stability to eliminate and prevent injuries, and improved overall health. And, it allowed individuals to utilize more body fat during a race, reducing reliance of foods and formulas. Many professional and amateur athletes, and trainers and coaches, use this system today.

As with AT, higher lactate levels reflect an anaerobic state. While this is very important to know during training, relying on lactate to know it is impractical. The test is not always reproducible, not always available with enough regularity for some athletes, and is associated with some cost. Keep it simple: just knowing the heart rate during different levels of activity can provide the same information.

Instead of a variety of different training zones, I prefer the simple distinction between two: aerobic and anaerobic. Just knowing you are above the max aerobic heart rate indicates anaerobic efforts. So, the lactate or anaerobic threshold is distinctly different from the maximum aerobic heart rate. And, one cannot obtain the max aerobic heart rate by measuring blood lactate or AT.

RQ and Max Aerobic HR

With proper protocol and interpretation, the respiratory quotient (RQ) is an effective treadmill test that provides athletes with the percent fat and sugar burning at various heart rates. This also helps determine the maximum aerobic heart rate, which is associated with the body’s ability to use high levels of fat for energy. As true aerobic training progresses, one will ultimately run or bike faster, for example, at the same heart rate because fat provides more fuel. Even without implementing anaerobic training, this will lead to faster race performances.

Unfortunately, RQ is still not commonly employed by coaches and athletes, despite the relative ease of today’s treadmill testing. However, the assessment is not widely available, and can be costly, especially considering follow up evaluations.

Based on many tests, including RQ, I developed the 180 Formula in the early 1980s. This allows athletes to find their maximum aerobic heart rate for use during training. In addition, the same heart rate is used to perform an important evaluation, the MAF Test, which helps monitor training progress (e.g., aerobic development and increased fat-burning).

I should add that, among the tests that remain popular, VO2max is also of little true value. For most athletes, the only benefit of performing this evaluation is that the process can sometimes also provide RQ data.

I no longer like lactate testing because there are more reliable, easier, and cheaper evaluations that all athletes can regularly utilize for effective training. Included are the 180 Formula, heart rate monitoring, and performing the MAF test. These can contribute significantly to the ultimate goal of both better performance and improved health.

Sprint Training: It’s Not Just Anaerobic

Sprint Training: It’s Not Just Anaerobic

Intervals are a popular method of performing cardio. In addition to being an effective way of developing anaerobic metabolism, which is the major reason people perform brief intervals, many people do intervals as a means of saving time. Because of the increased energy demands of an all-out sprint, exercise doesn’t need to be performed very long to at least feel like you’ve gotten a great workout.

But for overall effectiveness, there might still be reasonable doubts, not so much about the ability of intervals to work the anaerobic system, but instead about their effects on the aerobic system.Researchers looked into this topic in a recent study published in the Journal of Strength and Conditioning Research. They wanted to find out to what extent cardiovascular factors outside of just anaerobic contributions were worked by high intensity sprinting intervals.

One good reason for a study looking into these factors is the time savings itself, since this is one big reason to perform sprint intervals. But when thinking about this, you also have to consider what you’d be doing instead that might take longer. Since the anaerobic systems of the body have the biggest kick at the beginning of exercise, they don’t take long to push hard and develop progressively over time. The aerobic system, on the other hand, can sustain heightened energy outputs for hours on end, so this would be where sprints would save time. If sprinting interval programs work well for developing the aerobic system over a brief workout, then it may be worth it for the time-crunched among us.

In the study, the participants performed four all-out sprinting bursts on an exercise bike, each separated by four minutes of active rest. Active rest is typical in these types of maximum-intensity intervals. The down time is occupied by light activity without much or any resistance. In this case, the light activity was performed on the exercise bike with the resistance turned down to zero.

As mentioned before, sprinting is good for developing anaerobic metabolism, so the researchers assumed this as uncontroversial. Instead they looked at a few other performance factors associated more with aerobic work, such as VO2 max (the ability of your body to absorb, transport, and use oxygen), heart rate, and ventilation. Sure enough, these factors were all taxed by the sprinting intervals as well. The participants achieved 80% of their maximal values despite the small amount of actual hard work.

The results of this study point to the importance of the aerobic systems, even in such intense and brief sprints. The researchers hypothesized that the levels of cardiorespiratory stress achieved by this protocol were sufficient to potentially elicit aerobic benefits, which is pretty cool.

However, I’ll warn against misinterpreting this information. First, the tested program totaled eighteen minutes in length, including the four-minute rest periods. With the warm up included, the time goes up to about 23 minutes for this protocol. This isn’t all that much of a time savings compared to a brief warm up and two mile run that most people could achieve in the same amount of time. Since cardiorespiratory values were hit only briefly in this study, it’s possible that a two-mile run might be just as time-efficient, but a greater stimulus for other aspects of athletic improvement. Intervals are great for anaerobic work, and may even help a little bit with your aerobic work too, but ultimately, variety is key.

Do Your Intervals Count? What Science Says About Work-to-Rest Ratios | Breaking Muscle

Do Your Intervals Count? What Science Says About Work-to-Rest Ratios | Breaking Muscle.

Why Everything You Know About Lactic Acid Might Be Wrong

for references and full article click  Why Everything You Know About Lactic Acid Might Be Wrong

Admit it. For years you have blamed high-effort, short-term muscle fatigue on lactic acid accumulation. It’s all over exercise physiology texts and Internet sites. Lactic acid accumulation is the reason high-effort, short-term activities shut down the muscle activity sooner rather than later. Conventional wisdom, despite being based on antiquated research, does make sense. You work as hard as you can, lactic acid accumulates rapidly, you’re unable to oxidize it aerobically, your muscles then become acidic, and your effort deteriorates into a low-level effort or comes to a screeching halt.

This is a true scenario, but is lactic acid to blame? Here is an update on this belief and the new research that supports it.

lactic acid, lactate, pyruvate, glycolysis, energy systems, lactic acid buildupHigh-effort activity that requires the process of glycolysis(breakdown of stored muscle glycogen to produce ATP) results in the formation of lactic acid (pictured to the right). However, lactic acid is immediately split into lactate and hydrogen and does not remain as itself in muscle tissue. Lactate and hydrogen each face a different consequence.

Lactate may stay in the cells to be used as energy or move to active and inactive muscles and used as energy. The use of lactate as fuel within the muscle itself varies with how well a person’s endurance muscle fibers aretrained aerobically. Lactate can also be sent to the brain and heart for fuel, or to the liver to be converted to glucose.

The function of your brain is critical. When exercising, your body needs to maintain a steady supply of glucose to the brain to remain operational. Ever wonder why you get light headed following intense work? Yep, a lack of glucose supply. By the way, the manufacturing of new glucose in the liver during exercise is called gluconeogenesis. Interestingly, lactate is the most important facilitator of this process.

Great, but what then creates muscle fatigue if it’s not lactic acid accumulation?

Remember, glycolysis results in lactate and hydrogen formation. Hydrogen ion (H+) accumulation can increase muscle acidity, but most of it is buffered via the bicarbonate buffer system, then converted to water and carbon dioxide, and ultimately eliminated via expiration through the lungs. If the accumulation of lactate and hydrogen is extreme, someresearch evidence shows it may interfere with muscular contractions. However,recent evidence suggests this is questionable.

Come on, man! What then is the cause of muscle fatigue if not for lactic acid accumulation nor the aforementioned? Well, here is what scientists have concurredMuscle fatigue at non-sustainable workloads seems to be a result of the accumulation of other metabolites such as inorganic phosphates along with the inability to maintain the rate and force of contraction via the loss of potassium from inside muscle cells.

So, lactic acid itself as a muscle fatigue expeditor is nonsense? Let’s look at it another another wayTrainees or active humans obtain about one third of their total carbohydrate energy from lactate. The remainder is from circulating blood glucose and stored muscle glycogen. In order to burn lactate as fuel for muscles, you can either burn it directly or convert it to glucose and then burn it. In research on untrained subjects, about 75% of the lactate used was directly oxidized. In trained subjects, about 90% was directly oxidized. Trained subjects also burned more overall lactate. (So basically, it pays to be in shape.)

What does this mean? Endurance training stimulates the body to use more lactate and use it more efficiently. It was concluded in trained subjects that lactate is a preferred energy source over glucose. This spares glycogen stores, giving you more endurance.

Here are a few more tidbits to help clarify the issue:

When glucose is broken down through glycolysis the byproduct is pyruvate.Pyruvate can then be pushed into the Krebs cycle. This creates energy through the aerobic system or energy can be created via lactate. As you now know, lactate is not a waste product but a viable fuel source for continued muscle contraction. Converting pyruvate into lactate results in quicker energy production as opposed to the longer oxidative process.

lactic acid, lactate, pyruvate, glycolysis, energy systems, lactic acid buildup

How fast can pyruvate be converted into lactate? Recent research shows it’s dependent on the availability of oxygen. More oxygen equates to more pyruvate oxidized even though the amount is small. Regardless, if you’re in better shape, the glycolysis byproduct pyruvate can be converted to lactate and serve as future energy.

lactic acid, lactate, pyruvate, glycolysis, energy systems, lactic acid buildup

Lactate accumulation only occurs when its production is greater than its clearance. Here’s an example for you. Pour water down a drain slowly. The water drains at the same rate as it is poured. Now, pour the water at a higher volume and a greater flow will compromise drain’s ability to empty and the water level will rise in the reservoir.

Your body is similar to the aforementioned example. Lactate is cleared from the body by the liver, heart, brain, and muscles. Lactate produced by the large leg and back muscles can be used by other less active muscles such as the deltoids and abdominals.These less activated muscles – combined with oxygen intake – will convert lactate back to pyruvate to provide more fuel. Pyruvate can then be used aerobically in less taxed muscle or it can become recycled to support greater-demand contractions such as demanding lower-body exertions.

lactic acid, lactate, pyruvate, glycolysis, energy systems, lactic acid buildupFinally, to be an efficient energy source for another muscle group, lactate or pyruvate must be converted into a more efficient form.Therefore, circulating blood lactate is filtered through the liver where it is ultimately converted back into pyruvate, then to glucose through the gluconeogenesis process. The newly-formed substrate can then be returned to the muscle as an immediate fuel source or stored as glycogen to be used at a later time.

So, what can you take from this discussion?Lactic acid is not the cause of muscle fatigue as has been the common thought for years. Muscle fatigue and consequent inefficiency is due to the accumulation of other metabolites such as inorganic phosphates and the inability to maintain the rate and force of contraction via the loss of potassium from inside muscle cells.

Lactate production from high effort exercise is a good thing. Lactate is actually a provider of more energy for muscle contraction. Lactate also creates fuel for the brain and heart and can be converted to glucose in the liver.

In the end, lactic acid is not the issue. Lactate is, and it’s your pal!

5 Scientific Ways to Stop Muscle Cramps (And What Causes Those Annoying Cramps In The First Place).

Link to full article and references 5 Scientific Ways to Stop Muscle Cramps (And What Causes Those Annoying Cramps In The First Place).

WHAT PEOPLE THINK CAUSES MUSCLE CRAMPS

The most common explanation for what causes muscle cramps goes like this:1

When you exercise, your body sweats, releasing water and electrolytes like sodium, potassium, magnesium, calcium, and chloride.

As you continue to lose water and electrolytes during your workout, your body becomes depleted.

Electrolytes help conduct nerve impulses throughout your body, which allows your muscles to contract. When your body loses enough water and/or electrolytes, the nerve impulses from your brain to your muscles become deranged. This makes your muscles cramp.

This is why you’re told to consume sports drinks, electrolyte tablets, and lots of water during and around your workouts to help prevent or treat muscle cramps. Unfortunately, there’s almost no evidence this works.

WHY ELECTROLYTE LOSS AND DEHYDRATION PROBABLY DON’T CAUSE MUSCLE CRAMPS

There are four reasons why losing electrolytes and water probably doesn’t cause — or isn’t the primary cause — of your muscle cramps.2-5

1. Sweat contains far more water than it does electrolytes.

When you become dehydrated your blood levels of electrolytes actually rise or stay about the same.6

2. Athletes who get muscle cramps have about the same level of electrolytes and dehydration as athletes who don’t cramp.7

In some cases athletes who cramp have slightly higher magnesium levels.8 Other studies have found no relation of any kind between an athlete’s electrolyte levels and their risk of cramping — their risk of cramping was no higher or lower based on their electrolyte levels.9

Athletes who cramp also have about the same level of hydration as athletes who don’t.10

Another study found that drinking Gatorade did not prevent people from cramping (though there are a few problems with that study, so don’t get too excited).11

3. Not all of your muscles cramp.

If your cramps were caused losing too many electrolytes, then all or most of your muscles should cramp — not just some of them.

When people develop a real electrolyte deficiency, virtually all of their muscles go into uncontrollable spasms. On the other hand, athletes almost always get cramps in the muscles they’re using the most during their workouts. For example, in one study on ultra-marathon runners over 95% of all cramps occurred in the leg muscles during the race.8

4. Stretching, resting, and drinking pickle juice shouldn’t help stop cramps — but they do.

If muscle cramps were caused by dehydration and electrolyte loss, then there’s no good reason why stretching, resting, and sipping pickle juice should help cramps disappear — but they do.3

Stretching and resting a muscle doesn’t increase its electrolyte or water content, but both of these strategies do help muscle cramps go away.

In one study, pickle juice helped cramps disappear faster than drinking water or nothing at all.12 You might think that the salt and other electrolytes in the pickle juice were what stopped the cramps — not so. The cramps stopped long before the sodium from the pickles could be absorbed, so it didn’t work because it was replenishing lost electrolytes.13

WHAT REALLY CAUSES MUSCLE CRAMPS

The newest and most scientifically supported theory is that muscle cramps are caused by premature fatigue.2

As you get tired, your muscle’s reflex control becomes dysfunctional. Instead of contracting and relaxing like they’re supposed to, they keep firing. Basically, your muscles become “twitchy” and can’t stop contracting.

This theory is supported by several lines of evidence.

1. The muscles you use the most during your workouts are the ones that usually cramp.

2. Muscles that cross multiple joints are more likely to cramp than other muscles. These muscles generally have more activity during exercise when they’re more likely to get tired.

3. You’re far more likely to cramp during a race than you are in training — when you’re pushing yourself harder than normal. Cramps also tend to occur at the end of races when you’re most fatigued.

4. If you don’t pace yourself properly, you’re more likely to cramp. Athletes who go out too hard relative to their training experience are much more likely to cramp than those who stay within their limits.7,14

5. Drinking pickle juice helps cramps disappear faster than drinking water or nothing at all, and this happens before the salt from the pickle juice can be absorbed. Researchers think this is because the salty taste of the pickle juice “tricks” the brain into relaxing the muscles.12

6. Some evidence indicates that athletes who cramp have more muscle damage before races.14

At this point, there’s no direct evidence that consuming extra electrolytes will help you avoid muscle cramps. There’s some evidence that dehydration might be involved, but it’s almost certainly not the primary cause of your muscle cramps.

5 SCIENTIFIC WAYS TO STOP MUSCLE CRAMPS

1. Train specifically for your race.

Most cramps happen when you push yourself harder than you’re used to. If you make your training more similar to racing in terms of intensity and duration, then you’re probably less likely to cramp.

2. Rest.

If you get a cramp, the best way to get rid of it is to rest. Most cramps don’t last more than about 2-3 minutes at most.

3. Lightly stretch the muscle.

Some evidence indicates that light passive stretching can help muscle cramps go away faster than rest alone. You’re not trying to improve your flexibility with this stretching — just pull on the muscle lightly to tell the brain it’s okay to relax.

4. Drink pickle juice or another salty solution.

Drinking pickle juice may help your cramps disappear faster than drinking plain water or nothing. Since the effect is probably due to the acidic/salty taste, any similar drink or food would probably work well, too.

5. Stay hydrated.
There isn’t much evidence that dehydration causes muscle cramps, but it might contribute.11 It’s obviously worth staying hydrated for other reasons, so keep drinking when you’re thirsty.

REDUCE YOUR RISK OF MUSCLE CRAMPS

Nothing can guarantee that you’ll never get a muscle cramp. However, using the best available scientific evidence, you can reduce your chances significantly.

For prevention: Train smart and stay hydrated.

For treatment: rest, lightly stretch the muscle, and maybe drink something that tastes like salt or vinegar.

Half-Time and High-Speed Running in the Second Half of Soccer

Half-Time and High-Speed Running in the Second Half of Soccer

Response to R. Lovell’s and M. Weston’s Letter to the Editor
We thank Drs Lovell and Weston for their correspondence [4], and the Editor for the opportunity to respond to their letter. There appear to be a couple of substantive issues arising from their letter and several minor comments.
Firstly, our results are not “unique”, and the implication by Drs Lovell and Weston would appear to be unwarranted. We have directly validated the GPS equipment used in the study (which is clearly stated and referenced in the original manuscript [6]) and referenced other studies which found no difference in the distance completed by high-speed running when the first 15 minutes of each half of match play were compared in top class and moderate standard male ([5] please see Figure 3) and female players competing at international and domestic level ([1], please see Figure 1). While the pacing, in terms of changes in speeds of running across the 15-min periods of the matches, is potentially influenced by tactics and playing experience as well as the large variation between matches [2], it is unlikely that this explains the lack of difference in high speed running.
Lovell and Weston also question the “validity” of using the first portion of a football match (be it of 5 or 15 min duration) as an appropriate comparison period given its “intense and frantic nature” ([4], second paragraph). Their use of the word “validity” implies there is some accepted ‘gold standard’ or criterion approach; this is factually misleading. While there may be debate, and the 2 pieces of correspondence published here may be indicative thereof, the question is: What portion of a match should be used to compare or normalise against?
Given that players are at their least fatigued and, if they have completed a pre-match warm-up sufficiently close to kick-off, likely to be experiencing the benefits associated with elevated muscle temperature (see discussion paragraph 5), utilising the activity characteristics of the first 5/15 min of the first half to compare other portions of the match against would appear to be theoretically sound and justified. Although the correspondents may advocate a different approach, I am sure they know the one used in our manuscript is the one chosen by a number of other authors, including themselves on occasion. While Drs Lovell and Weston might advocate a different approach, that taken in our paper is perfectly reasonable and allows comparison with previous research; deciding which portions of a match to ‘normalise’ against is quite reasonably open to debate. As such it is appropriate that it encourages academic dialogue.
Lovell and Weston also note that passive half-time intervals cannot be assumed in time-motion studies. This is a valid point generally but, as we did not assume this, it is not relevant with respect to our study. We observed and recorded what the players who participated in our study did prior to play and at half-time, as clearly described in our methods. They also make reference to a “strong assertion” we apparently made regarding the efficacy of re-warm-up. The statement to which they refer (discussion first sentence, paragraph 5) is part of a substantial paragraph discussing our study’s findings and its implications. Our study found that even with a pre-match warm-up, there was no difference in high-speed running completed when the first 5 /15 min of play was compared with the same period post-half time when there was no re-warm-up. As outlined in the paper, there may be a number of possible reasons for our observations, but the delay between the end of warm-up or re-warm-up and the commencement of competitive play is probably key (discussion paragraph 5). The paper never advocated the elimination of warm-up or re-warm-up. We merely examined what was happening in real competitive conditions and discussed some of the potential implications arising from these observations. It is not enough to demonstrate that something can work in a laboratory or otherwise optimal conditions if a key aim is to subsequently apply a particular procedure in non-laboratory or less than optimal conditions. It is essential to know what happens in practice and in turn what are the implications of this. Given the delays that may occur between the end of a warm-up and the beginning of competitive match play in many situations and the necessity for other activities such as tactical discussions at half-time, it is simplistic to assume that any warm-up will be beneficial in performance terms (see paragraph 5). While the correspondents are entitled to their interpretation, we do not believe that when the paragraph and associated paper is read in its entirety their interpretation is inevitable.
We are happy to have our attention drawn to 2 papers by the correspondents [3] [7], but clearly their findings could not have been considered in the paper we published as they were not in the public domain at the time of its submission. Given the ever increasing volume of research and the guidelines set by journals it is inevitable that there will be some debate among authors, reviewers and indeed readers, regarding which academic papers should be referenced and which should not. We feel we gave due acknowledgement to the weight of available evidence given that this was a research paper and not a review. If the correspondents feel there was insufficient acknowledgement to their work, it was not deliberate and clearly their correspondence will go some way in addressing any perceived oversight.
We believe that acknowledging weaknesses in one’s work is an integral part of the scientific process and we have tried to acknowledge any shortcomings. In hindsight it may well be that an alternative analytical strategy (multi-level modelling) may have been a more optimal analysis methodology. There is clearly scope for further research investigating how both warm-ups and re-warm-ups at half-time impact soccer performance. Our paper “Half-Time and High-Speed Running in the Second Half of Soccer” provides an observational description of what actually occurs during competitive soccer matches.

Is altitude training appropriate for football (soccer) players? New evidence

A nice study was published about two weeks ago by McLean and colleagues from Australia on 30 elite Australian Football players. Twenty one of them completed 19 days of living and training at moderate altitude (around 2130 m) whereas the remaining 9 served as the control group (sea level training). Time-trial running performance in 2000m and hemoglobin mass were assessed before, immediately after the intervention as well as 4 weeks after returning from altitude in both groups.
Main findings
  • Running performance improved in both conditions. However, the improvement in 2000 m performance was 1.5% greater after altitude training compared with sea level.
  • This beneficial effect was maintained after 4 weeks of altitude training cessation.
  • Hbmass increased by 2.8% with altitude training but returned to baseline values at 4 weeks after returning to sea level.
Conclusion & comments
As the authors suggest the maintenance of  running performance improvement at 4 weeks after returning from altitude suggests that altitude training may be beneficial to performance in team-sport athletes. It is worth noting, however, that no testing was conducted in the control group at that time. Hence, we don’t know if the performance maintenace at 4 weeks postdescent was due to altitude training per se.
Finally, whether this benefit translates into improved match running performance in football (soccer) remains to be proven.
Source
McLean, Buttifant, Gore, White, Liess and Kemp (2013). Physiological and performance responses to a preseason altitude-training in elite team-sport athletes. Int J Sports Physiol Perform 8:391-399.