( ( 6 ( Exercise training ) ) ( ( ( ( increases ( cardiovascular ( functional capacity ) ) ) and ) ( ( decreases ( myocardial ( oxygen demand ) ) ) ( ( ( at ( ( any level ) ( of ( ( physical activity ) ( in ( ( apparently healthy ) persons ) ) ) ) ) ) ( as ( well as ) ) ) ( in ( ( most subjects ) ( with ( cardiovascular disease ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (CD 6) (NNP Exercise) (NN training)) (VP (VP (VBZ increases) (NP (JJ cardiovascular) (JJ functional) (NN capacity))) (CC and) (VP (VBZ decreases) (NP (JJ myocardial) (NN oxygen) (NN demand)) (PP (PP (IN at) (NP (NP (DT any) (NN level)) (PP (IN of) (NP (NP (JJ physical) (NN activity)) (PP (IN in) (NP (ADJP (RB apparently) (JJ healthy)) (NNS persons))))))) (CONJP (RB as) (RB well) (IN as)) (PP (IN in) (NP (NP (JJS most) (NNS subjects)) (PP (IN with) (NP (JJ cardiovascular) (NN disease)))))))) (. .)))
6 Exercise training increases cardiovascular functional capacity and decreases myocardial oxygen demand at any level of physical activity in apparently healthy persons as well as in most subjects with cardiovascular disease.
(ROOT (S (NP (NP (NN Smoking) (NN tobaccowould)) (ADJP (RBS most) (JJ likely))) (VP (VBP have) (NP (NP (DT a) (JJ negative) (NN impact)) (PP (IN on) (NP (NP (DT the) (NN ability)) (PP (IN of) (NP (DT an) (ADJP (JJ individual) (S (VP (TO to) (VP (VB succeed) (PP (IN at) (NP (JJ physical) (NNS activities))) (SBAR (IN because) (S (NP (PRP it)) (NP (PRP it)))))))) (NNP decreases) (NN stamina) (CC and) (JJ cardiovascular) (NN efficiency))))))) (. .)))
Smoking tobaccowould  most likely have a negative impact on the ability of an individual to succeed at physical activities because it it decreases stamina and cardiovascular efficiency.