STRENGTH | MUSCLE – SATELLITE CELLS | O2 DELIVERY | CAPILLARIZATION – AGING


8 RESEARCH ARTICLES + 1 GRAPHIC – CLICK ON GRAPHIC TO ENLARGE


– MUSCLE FIBRE PERFUSION: the process of oxygenated blood being delivered to the tissues of the body
– CAPILLARIES: any of the fine branching blood vessels that form a network between the arterioles and venules
– CAPILLARIZATION: Formation and development of a network of capillaries to a part of the body; increased by aerobic exercise
– SATELLITE CELLS: “Skeletal muscle satellite cells act as a reserve population of cells, able to proliferate in response to injury and give rise to regenerated muscle and to more satellite cells” – Source




Snijders, Parise et al
INTRODUCTION

– Muscle fibre capillarization is known to decrease substantially with advancing age
METHODS
– 22 healthy older men (71 ± 1 yrs) did 24 wks of progressive resistance type exercise training
– A comparison was made between participants who had:
(a) low type II muscle fibre capillary-to-fibre perimeter exchange index (CFPE; LOW group)
(b) high type II muscle fibre CFPE (HIGH group) at baseline
RESULTS
1. Type II muscle fibre size and satellite cell content increased in response to 24 wks of RT
2. These improvements where mainly driven by differences in baseline type II muscle fibre capillarization
3. Muscle fibre size and satellite cell content increased significantly in the HIGH group

4. No significant changes in type I and II muscle fibre capillarization observed in 12 and 24 weeks of RT training in both groups


RESISTANCE TRAINING INCREASES MUSCLE CAPILLARIZATION IN OLD MEN – 2016


Verdijk, Van Loon et al
INTRODUCTION

– Skeletal muscle capillarization plays a key role in oxygen and nutrient delivery to muscle
– Loss of muscle mass with aging and anabolic resistance have been attributed to changes in skeletal muscle capillary structure and function
METHODS
– Muscle biopsies from the vastus lateralis before and after 12 wks of resistance type exercise training
– Healthy young (n=14, 26+/-2 y) and older (n=16, 72+/-1 y) adult men, 

– Assessed skeletal muscle fiber size, capillary contacts per muscle fiber (CC), and capillary-to-fiber perimeter exchange (CFPE) index in type I and II muscle fibers
RESULTS
(1) Type II muscle fibers were smaller in old vs young
(2) Type I and type II muscle fiber CC and CFPE index were smaller in old compared with young muscle
(3) Resistance type exercise training increased type II muscle fiber size only
(4) CC and CFPE index increased in both the type I and type II muscle fibers following 12 weeks resistance training in older men.
CONCLUSION
– Greater capillary supply may be an important prerequisite to reverse anabolic resistance and support muscle hypertrophy


STRENGTH TRAINING IMPROVES MUSCLE AEROBIC CAPACITY & GLUCOSE TOLERANCE – 2016


Frank P1,2Andersson E1,3Pontén M1Ekblom B1Ekblom M1Sahlin K1.
AIM

Investigate the effect of short-term resistance training (RET) on mitochondrial protein content and glucose tolerance in elderly
METHODS
– Elderly women and men (age 71 ± 1, mean ± SEM) were assigned to a group
A) performing 8 weeks of resistance training (RET, n = 12)
B) No training (CON, n = 9).
RESULTS
– The RET group increased:
(i) knee extensor strength (concentric +11 ± 3%, eccentric +8 ± 3% and static +12 ± 3%)
(ii) initial (0-30 ms) rate of force development (+52 ± 26%)
(iii) contents of proteins related to signaling of muscle protein synthesis
– Muscle fiber type composition changed to a more oxidative profile in RET
– Increased type IIa fibers (+26.9 ± 6.8%) and a trend for decreased amount of type IIx fibers (-16.4 ± 18.2%)

– Mitochondrial proteins increased in RET
– RET improved oral glucose tolerance
– In the CONTROL Group parameters were unchanged or impaired


 SATELLITE CELLS LOCATED CLOSER TO CAPILLARIES IN YOUNG VS. OLD MEN – 2016


Nederveen JP1Joanisse S1Snijders T1Ivankovic V1Baker SK2Phillips SM1Parise G3.
BACKGROUND

– Satellite cells (SC) are instrumental in maintenance of muscle fibres and the adaptive responses to exercise
– There is an age-related decline in SC

– A spatial relationship exists between SC and muscle fibre capillaries
METHODS
– Untrained young men (YM, 24 ± 3 yrs; n = 23) and older men (OM, 67 ± 4 yearsn = 22) at rest
– A subset of YM (n = 9) performed a single bout of resistance exercise
RESISTANCE TRAINING ↑ SATELLITE CELL NUMBER AND PROXIMITY TO CAPILLARIES
(1) Type II muscle fibre SC and capillary content was significantly lower in the OM compared with YM
(2) Type II muscle fibre SC were located at a greater distance from the nearest capillary in OM compared with YM 
(3) In response to a single bout of exercise, we observed a significant increase in SC number and activation status
(4) In addition, activated vs. quiescent SC were situated closer to capillaries


THE EFFECT OF EXERCISE MODE ON SATELLITE CELLS IN OLD MEN – 2015


Nederveen JP1Joanisse S1Séguin CM1Bell KE1Baker SK2Phillips SM1Parise G1,3.
AIM

– A dysregulation of satellite cells may contribute to the progressive loss of muscle mass that occurs with age
– However, older adults retain the ability to activate and expand their satellite cell pool in response to exercise
METHODS
– Sedentary older men (n=22; 67±4yrs) were randomly assigned to complete:
(a) resistance exercise
(b) high intensity interval exercise on a cycle ergometer
(c) moderate intensity aerobic exercise
RESISTANCE TRAINING FOLLOWED BY HIIT
– Resistance Exercise is the most potent exercise type to induce satellite cell pool expansion
– High intensity interval exercise was more potent than moderate intensity aerobic exercise in inducing satellite cell activity


SATELLITE CELL RESPONSE TO A SINGLE BOUT OF RESISTANCE EXERCISE DELAYED IN AGING MEN – 2014


Snijders T1Verdijk LBSmeets JSMcKay BRSenden JMHartgens FParise GGreenhaff Pvan Loon LJ.
INTRODUCTION
– Satellite cells (SCs) have been shown to be instrumental in the muscle adaptive response to exercise
METHOD
– 10 
young (22 ± 1 years) and 10 elderly (73 ± 1 years) men performed a single bout of resistance-type exercise
LONGER RECOVERY FOR OLDER MEN
– In response to exercise: It took 48 h (young) and 72 h (elderly) for type II muscle fiber SC content to exceed baseline values
– The increase in type II muscle fiber SC content during post-exercise recovery is delayed with aging and is accompanied by a blunted SC activation response


SATELLITE CELLS IN MUSCLE FROM BIRTH TO OLD AGE – 2014


Verdijk LBSnijders TDrost MDelhaas TKadi Fvan Loon LJ.
BACKGROUND

– Changes in satellite cell content play a key role in regulating skeletal muscle growth and atrophy
METHOD
– Muscle biopsies were collected in 165 subjects, from different muscles of:
(1) Children undergoing surgery (<18 years; n = 13)
(2) From the vastus lateralis muscle of young adult (18–49 years; n = 50)
(3) From the vastus lateralis muscle of older adults (50–69 years; n = 53)
(4) From the vastus lateralis muscle of senescent subjects (70–86 years; n = 49)
(5) In a subgroup of 51 aged subjects (71 ± 6 yrs), additional biopsies were collected after 12 wks of supervised resistance-type exercise training
RESISTANCE TRAINING ↑ SC AND TYPE 2 CELLS
(1) Type II muscle fiber size was substantially smaller with increasing age in adults
(2) This was accompanied by an age-related reduction in type II muscle fiber satellite cell content
(3) 12 weeks of resistance-type exercise training significantly increased type II muscle fiber size and satellite cell content


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