July 2024
What We Mean When We Say “Activate” Muscles
A readily-bandied about if not overused phrase in the fitness arena is “activate your _____ muscles”. Intuitively, we understand its meaning but a recent study out of the UK will give it more currency.
They studied what they call ‘force steadiness’ in subjects with and without chronic low back pain (CLBP). This is based on a concept observed in people with pain or injury that muscles around the joint do not respond appropriately in terms of timing and force production.
Using electromyography, they measured the neural (nervous system) commands that control muscle contraction. They sought to determine if “any impairment in [force control] can negatively affect the precision of voluntary movements, resulting in alterations in dynamic joint stability…” In essence, if muscles around the spine can’t control micromovement, pain is likely to result.
They tested torque production at low levels of intensity during simple sub-maximal trunk flexion and extension to see how and if those with CLBP could control small movements concentrically and eccentrically of the spine.
As one might expect, those with pain had “poorer trunk extensor muscle torque steadiness”, “poorer trunk flexor muscle control and higher activation of abdominal muscles [considered unnecessary for the movement]”, and a “higher contribution of the abdominal muscles…to the resultant torque during concentric contractions.”
All this to say, those with CLBP are activating the wrong muscles the wrong way with the wrong intensity. In other words, let’s activate properly.
MSSE Feb. 2024
Frailty = Increased Body Mass = Lower Aerobic Capacity
“Deficit accumulation frailty” refers to the “age-related deficits in clinical characteristics, disease states, behaviors, and function” that portend reduced quality and quantity of life. We know that lower cardiorespiratory fitness (CRF) and physical capacity accelerate during aging but we do not know if those who intentionally improve their CRF, especially if they also lose excess weight, through lifestyle reverse the aging processes associated with frailty.
Over a 4 year period, data collected on 3944 participants (ages 45-76) with type 2 diabetes and overweight/obesity allowed researchers to see if an intervention program succeeded in slowing the risk of increasing their frailty index (FI). One group was assigned to the intensive lifestyle intervention (ILI) of reduced caloric intake and increased physical activity to lose weight, improve CRF, and improve risk factors like cholesterol, blood sugar, and blood pressure; the other group attended group sessions aimed providing diabetes support and education (DSE) with the same educational materials as the ILI group.
As hoped for, those in the ILI had reduced body weight/body mass index (BMI) and/or improved CRF, slowing the progression of FI.
Those who’d improved both had more robust reductions in their FI.
It is noteworthy that (1) this is the first study to demonstrate a long term benefits from making lifestyle changes and (2) the benefits accrued to each change independently – getting fitter OR losing weight. In other words, move more, eat less!
MSSE Apr. 2024
Tid Bits
A very large, Harvard-led study (Am J of Clinical Nutrition Oct. 2023) that followed over 200,000 people for up to 36 years found that “those who regularly ate the highest amounts [or red meat] – averaging about a serving each day – were 53% more likely to develop diabetes than those who ate the least” amounts. Those who had a serving of nuts or beans instead of red meat were 30% less likely to develop diabetes. Harvard Women’s Health Watch, Feb. 2024
This is an interesting weight lifting phenomenon: the total capacity of lifting with both limbs adds up to less than the sum of each limb’s capacity. This bilateral deficit is befuddling. A study was performed to investigate the roots of this truism. Using bilateral (BL) and unilateral (UL) maximal knee extension exercises, it found that there is about a 10% deficit in force production but not in EMG activation. In conclusion, “the bilateral deficit was not associated with a neuromuscular deficit” meaning, neural drive is not the source of the deficit and may be used to potentiate subsequent BL lifts. JSCR Mar. 2024
The normal fluctuations of sex hormones that females experience monthly have been associated, by athletes themselves, as having an impact on training and competition. If and how the menstrual cycle (MC) impacts performance remains a mystery. Looking at the 3 phases of the MC in 21 elite, normal-cycle, endurance athletes performing a variety of cardio workouts, they found that there was “no effect of MC phase or the serum concentrations of estrogen and progesterone on peak oxygen uptake…, time-to-exhaustion, running economy, or mean 30-s power output (MPO30s). Serum testosterone concentration was positively associated with MPO30s.” As such, it appears that no “single MC phase is consistently associated with” performance on a group level but individual responses may vary. JSCR Mar. 2024
