The Canadian Society for Exercise Physiology (CSEP) made headlines last week with the release of their New Physical Activity Guidelines . I am very happy that exercise is making the news.  The only problem is that the New Guidelines are not new.

“To achieve health benefits, adults aged 18-64 years should accumulate at least 150 minutes of moderate- to vigorous-intensity aerobic physical activity per week, in bouts of 10 minutes or more.”[1]

How is this different from last year’s New Physical Activity Recommendations:

“Adults should get at least 150 minutes/week of moderate intensity physical activity (such as brisk walking, swimming or raking leaves). This can be achieved in a variety of ways, for example 30 minutes 5 days a week.  Activity can be broken into smaller bouts at least 10 minutes long.  If activity is vigorous (such as jogging, hockey or aerobics), health benefits can be achieved with 90 minutes/week.  In general, the more time spent being active and the more intense the activity, the better. ” [2]

I suppose the new guidelines have a brevity factor that the old ones did not have.

I decided to look at the recommendation more closely to find out what is behind it, which lead me to “A systematic review of the evidence for Canada’s Physical Activity Guidelines for Adults”. This document summarizes the literature review that was done as the basis for the new recommendations. It is clear that a detailed assessment was performed, with the guidelines based on the impact of exercise on seven chronic diseases:

1. cardiovascular disease
2. Stroke
3. Hypertension
4. colon cancer
5. breast cancer
6. type 2 diabetes (diabetes mellitus)
7. osteoporosis

The recommendations echo those of the World Health Organization (WHO), which states that “everyone should engage in at least 30 minutes of moderate physical activity every day. More activity may be required for weight control.” [4]  Similar, except it would seem Canadians get to take the weekend off.

The WHO recommendation refers back to a US Department of Health & Human Services Committee Report, “Physical Activity Guidelines Advisory Committee Report, 2008”, which is also a literature review of the impact of exercise on 7 health outcomes: [5]

1. cardiorespiratory health
2. Metabolic health
3. Musculoskeletal health
4. Cancer
5. Functional health
6. Mental health
7. All-cause mortality

The 7 US health outcomes are slightly different from the 7 Canadian chronic diseases. The US review appears to have slightly more rigour in the presentation of the methodology, in that it identifies the questions it tries to answer for each health outcome: [6]

1. Is there sufficient evidence that physical activity is associated with [Outcome]?

2. Is there sufficient evidence to support differing intensities of physical activity in relation to the association with [Outcome] or precursors?

3. Is there sufficient evidence that the accumulation of multiple short periods of physical activity is associated with [Outcome] or precursors?

4. Is there sufficient evidence of increased risk with physical activity associated with [Outcome]?

5. Is there sufficient evidence that supports a pattern of weekly regularity (days per week) of physical activity and association with [Outcome] or precursors?

6. Is there sufficient evidence that different modes (types) of physical activity are (differentially and similarly) associated with [Outcome]?

7. Is there sufficient evidence that a physical activity exposure other than 30 minutes per day on most, preferably all, days each week is associated with [Outcome]?

The most important question about the guidelines: Is this a good recommendation?

I am not so sure. It seems like they are aiming for a “baby steps” approach.  This may be the right approach from a communications standpoint because it will not overwhelm anyone. But I wonder if they have aimed too low. From my perspective as a personal trainer, it definitely comes up short in terms of overall exercise volume. Should we really be recommending the bare minimum? I have never seen success result from reaching for the lowest rung.

As a strength coach, I would have preferred to see a recommendation that had a greater focus on strengthening than on aerobic exercise.  Both the old “New Physical Activity Recommendations” and the new “New Physical Activity Guidelines”, do refer to strength training, but it is more of an afterthought. The New New Guidelines state that “It is also beneficial to add muscle and bone strengthening activities using major muscle groups, at least 2 days per week.”[1]  The Old New Guidelines say “The physical activity should be mostly aerobic activity, and should include muscle and bone strengthening activities 2 to 4 days a week, and flexibility activities 4 to 7 days a week.” [2]

I suppose I should be happy that strength training is mentioned at all. But I am not one to reach for the bottom rung. There is substantial evidence to suggest that strength training is a better option than aerobic activity for weight loss, although the WHO recommendation document, suggests otherwise:

“There is a favourable and consistent effect of aerobic physical activity on achieving weight maintenance. accumulation of energy expenditure due to physical activity is what is important to achieving energy balance. Accumulation of physical activity can be obtained in short multiple bouts of at least 10 minutes, or one long bout to meet physical activity expenditure goals for weight maintenance. The evidence is less consistent for resistance training, in part, because of the compensatory increase in lean mass, and the smaller volumes of exercise employed.”[4]

That doesn’t read well for me, particularly the bold part (added by me). What does that mean? I think they’re trying to say that resistance training is not as good as aerobics because it helps build muscle instead of losing weight.  Um. That’s a bad thing?

Where adequate background research was found about the impact of resistance training, it was a positive correlation in both the Canadian and US documents. From the Canadian document:

“Katzmarzyk and colleagues [126,154,158] in Canada have also demonstrated a positive relationship between musculoskeletal fitness and health status. For instance, Katzmarzyk and Craig (2002) revealed that there was a significantly higher risk of premature mortality in the lower quartile of sit-ups in both men (RR = 2.72) and women (RR = 2.26). Grip strength was also predictive of mortality in men (RR = 1.49), but not women. In a recent study, Mason et al. revealed that musculoskeletal fitness was a significant predictor of weight gain over a 20-year period [158]. Importantly, they also reported that individuals with low musculoskeletal fitness had 78% greater odds of significant weight gain (? 10 kg) compared to those with high musculoskeletal fitness. These studies provide direct support for the inclusion of resistance and flexibility training in Canada’s physical activity guidelines for adults [3,159].”[3]

The US document showed improvement in bone mass density (BMD) for resistance training in most studies reviewed, but one study showed no improvement in BMD for the hip region. The suggested reason?

“This would be expected if RT programs did not include exercises that specifically involved the musculature in the hip region, particularly because many of the exercises that target other major muscle groups are commonly performed in the seated position (i.e., very little load on the FN and other regions of the proximal femur).” [7]

Very interesting! This is a good argument to progress aging clients to using free weights instead of machines for their strength training.

In the end, I think the good news is that exercise made the headlines, and hopefully has some people thinking that it is time for them to get moving. The bad news is that they set the standard very low, and, in my opinion, place their focus on the wrong exercise. But I will take Canadians doing 30 minutes of aerobic exercise 5 days a week over spending that time on the couch eating chips.

References:

[1] http://www.csep.ca/CMFiles/Guidelines/CSEP-InfoSheets-adults-ENG.pdf

[2] http://www.participaction.com/ecms.ashx/PressReleases/en/CSEP_PAC-FactSheet-FINAL-EN.pdf

[3] http://www.ijbnpa.org/content/7/1/39

[4] http://whqlibdoc.who.int/publications/2010/9789241599979_eng.pdf

[5] http://www.health.gov/PAGuidelines/Report/pdf/CommitteeReport.pdf , p. 122.

[6] http://www.health.gov/PAGuidelines/Report/pdf/CommitteeReport.pdf ,  p. 121.

[7]http://www.health.gov/PAGuidelines/Report/pdf/CommitteeReport.pdf ,  p. 316