Table 4.

Studies with Twin Response to Exercise

PA Intervention	Outcomes	H-effect	MZ (n)	DZ (n)	Sex	Comments	Ref
Submaximal supine bicycle at HR of 110bpm	End-diastolic mean wall thickness (rest)	H = 53%	21	12	M	Similar results when adjusted for body fat. Non-genetic component is made up of both shared and non-shared environmental components.	(40)
	LV diameter (rest)	N.S
	Fractional shortening (rest)	H = 13% (N.S)
	Change in End-diastolic mean wall thickness w/exercise	H = 0% (N.S.)
	Change LV diameter w/exercise	H = 24%
	Change in Fractional shortening w/exercise	H = 47%
	Cycling Power output	H = 53%
	Cycling VO2max	H = 46%
20-wk endurance training	LV wall, posterior wall, septal wall, LV mass,	Minimal H effect	20	20 (not related)	M	Training effect in all subjects.	(303)
Supine bicycle at 60W (submaximal)	SBP (rest)	Sig H	32	21	M	Less effect on heritability during exercise than at rest (conclusions based only on abstract; unable to obtain full article)	(41)
	DBP (rest)
	Change in SBP w/exercise
	Change in DBP w/exercise
Graded Cycle test to “exhaustion”	Peak VO2	H = 77%, 66% when PA and skinfolds adjusted	29	19	M	Testing was done on a max test and also collected with HR was at 150bpm.	(176)
	O2 uptake at HR of 150bpm	H = 61%, 16% when PA and skinfolds adjusted
	Mechanical Efficiency	N.S. H Correlation
	Anaerobic energy generation	H = 78%, 58% when PA and skinfolds adjusted
	Respiratory exchange ratio	H = 6% only
30 minutes of treadmill at anaerobic threshold	GH and PRL response to exercise and cortisol at rest	Sig H Correlation	9		M	Athletes	(135)
	ACTH and cortisol response to exercise and beta-endorphin at rest	N.S. H Correlation
93 days of negative energy balance (diet and exercise)	euglycemic-hyperinsuliemic clamp before and after intervention	N.S. H Correlation	7		M		(390)
	Fasting and postprandial insulin
	dehydroepiandrosterone sulfate & androsterone glucuronide	Sig. H effect	7		M	Healthy Young Males.	(419)
	Cortisol levels
Wingate test, max progressive test	Max 5 s Wingate power	H = 74%	8	8		Not correlated were measures in the ergojump test. Had different heritability's with different tests measuring same performance measure. Homogenous subject group.	(75)
	Max Lactate Wingate	H = 82%
	Delta Lactate during maximal test	H = 84%
10-wk isokinetic strength training (5d/wk)	HK, MDH, B-HAD	N.S. H	5	5 (unrelated)	M		(505)
	oxoglutarate dehydrogenase activity (OGDH)	Sig H
Maximal and submaximal treadmill running	running economy	N.S. H Correlation	8	8		No significant differences in references to MZ v DZ twins.	(440)
	VO2 max	N.S. H Correlation
	Maximal lactate	H = 75%
15 weeks of endurance training	Skeleteal Muslce HKII, (31%), PFK (37%), LDH (21%), MDH (31%), &B-HAD (60%)	Sig H	12		M		(217)
	fiber-type, CK activitiy,	N.S. H
15 weeks of high intensity supramaximal exercise (4–5 times/wk)	ALC, CK, HK, LDH, MDH, OGDH activitiy & PFK:OGDH activity ratio	Sig H	28			Exercise bouts of 15–90s all out.	(474)
	fiber type & anaerobic capacity
A single 90 minute bout of exercise	Rest v Ex Adipose LPL activity following exercise	Sig difference btw MZ and DZ	11	10	M	Aged 18–27	(458)
Cycle exercise	Rest v Ex metabolic rate(VO2)	H = 46% at low power. N.S. H at > 6xRMR	37	21 + 31 parent child	B		(60)
Cycle exercise to max	Absolute and BW adjust VO2max	Sig H	12	12	M	18–31 years old	(177)
	Rest v Ex LV internal diameter	N.S. H
	Rest v Ex Fractional Shortening	N.S. H
	LV Mass	N.S. H when adjusted for BW
165 min submax treadmill test before & after 22 days of 1000 kcal/day overfeeding	Pre v Post change in VO2max	Sig H	12		M		(524)
93 days of supervised 60min/d exercise	Loss in B.W., fat mass, skinfold, visceral fat	Sig H	7		M	Healthy young males	(59)
	Change in fasting TAGs and Cholesterol
	Change in VO2max, RER during exercise
1000 kcal of vigorous exercise per day for 22 days	Pre v Post fasting insulin	Sig H	12		M	Healthy young males.	(522)
	Pre v Post delta insulin during OGTT	N.S. H
93 days of supervised 60min/d exercise	Pre v post fasting insulin and glucose disposal	N.S. H, but Sig improvement	7				(390)
116min/day of cycle ergometer for 22days at 58% max	Pre v Post fat mass	N.S. H	12		M	Healthy males aged 19.1 yr old.	(414)
	basal lipogenesis	Sig H
	Pre v Post insulin stimulated lipogenesis	N.S. H
	Pre v Post epinephrine and basal lipolysis	N.S. H
	Pre v Post LPL activity	N.S. H
	Fat Free Mass	Sig H
20-wk cycle ergometer endurance training	Pre vs. Post epinephrine lipolysis	Sig H.	8		B	4 male and 4 female.	(133)
	Basal lipolysis	N.S. H
Single 90 min bout of exercise	LPL activity	More Sig in MZ than DZ	11	10	M		(458)
116 min/day of cycle ergometer for 22days at 58% max	Total Cholesterol	Sig H	12		M		(134)
	LDL Cholesterol
	HDL Cholesterol
93 days of supervised 60min/d exercise	Total cholesterol	Sig H	7		M	Male, young and healthy. ~93000 total calorie deficit. Significant within twin effects.	(298)
	LDL Cholesterol
	Cholesterol to HDL ratio
116min/day of cycle ergometer for 22days at 58% max	Baseline RMR	Sig H	12		M		(415)
	Baseline thermic effect of food
	Pre v Post plasma T3, T4, and FT4	Sig H (except for T3)
93 days of supervised 60min/d exercise	Pre v post RMR, Thermic effect of food,	Sig H	7		M	Healthy young males	(523)
	Thyroid hormones
14 weeks of exercise training	Cardiac Size	N.S. H	28	10 + 12 siblings	B	No genetic effect on heart size pre or post exercise training.	(3)

B = both; DZ= dizygotic; H = heredity effect; M = male; monozygotic; N.S. = non-significant; n = number of subjects