I will not keep you in suspense for a long time:
I do not consider anything wrong with both sexgymnastics and hetero-handjob.
Just contrary: they are safe & healthy!

What prevents us, then, from practising them?
This answer will be much longer, yet worth reading, since - as it was said - they are safe & healthy.

And though they are that recommendable, we do not practise them since we consider several their features as "immoral"...

Before comparing the traditional and new features of sex-behaviour, let us describe what sexgymnastics and hetero-handjob are:

Let us presume that our entire body is sexual. In this perspective, they are but two steps in one technique.
Sexgymnastics means a link between sport and the (contact, yet safe) sex. Hetero-handjob is the final leading my partner to orgasm by the direct teasing her/his erogenous zones by hands (or let us add the option of a sex-toy).  [In the "gyno" category of porn, the medical gloves are visible quite often, which is certainly proper in the case of swinging.]

It is everything - and you may be asking what is new in it? You are right: there is no new element, but their mixture and the relevance of them, if compared with the traditional approach.

old: risky intercourse	new: safe outercourse
The traditional standard of what is called "sex" - penis in vagina - is risky both for the Sexually Transmitted Diseases and for unplanned pregnancy.	Safe sex, in both aspects.

old: alienation	new: mutuality
"Sex" is a sort of "goods", i.e. for money.	Sex pleasure and satisfaction in context of a sport-club friendly milieu.

old: dance and sport	new: complete sex-curve as the leading factor
Though both dance and sport are pleasurable in the carnal sense -  including the sexual pleasure - their rules presume as their aim something else. The higher level of sexual excitement is but a co-incindece (which sometimes occurs, though...).	Sexgymnastics aims explicitly at  full sex-excitement and satisfaction with the plateau long as only possible.

old: sport-dress	new: nudity
Both dance and pair-sports are dressed. Nudity but for intercourse.	The nudity, already common from the naturist beaches and www-porn, now enjoyed in our couple sexy-sport, sexgymnastics.

old: awkward genitals	new: expertly hands
Historically linked to procreation, the satisfaction is attained in hope that the genitals were created optimal (not only for procreation but also for the pleasure). Low level of expertise concerning the opposite-sex genitalia and erogenous zones.	Ideal is to know-how with my partners' erogenous zones as with mine.

old: voyerism	new: exhibitionism
Tradition to "peep" (as a customer or as a thief).	Activity, devotion and passion lead to the pleasure of my show-off. Onlooking is supposed, yet not necessary since the naked gymnastics is pleasurable in itself.

old: onlooking	new: participation
Professionals are practicing sex on the stage. Onlookers sit: there is a gap between the "professionals" and (onlooking ...and paying) "amateurs". [An amateur involved but as "a guest".]	We ourselves practice. Participants are active as sport-persons. Sexgymnastics is for free.

old: frotteurism	new: bodily contact
Who touches another person is a harassing aggressor.	Both partners enjoy their bodily contact. The excited bodies can be treated quite radically!

old: patriarchate	new: androgyny
Woman (as if)  subordinate and passive.	Both sexes equal.

old: hidden excitement	new: overt excitement
The hypocrisy concerning excitement has led to Viagra.	Sexual excitement of both sexes is an integral part of all the activities. It is considered healthy and proper.

old: couple	new: group option
The couple standard ensues from the family-context sex.	By the safe-sex techniques, a group or "1 plus more" option are possible, though not obligatory.

old: ideal	new: carnal
After the porn-magazines have conquered the sex-stage, the sex seems to smell with the print of photos.	Not only the mutual oil massage, but also the pleasure of common, shared sweating. For wrestlers quite common; by the today's hetero-couples but among dancers, and while a long intercourse.  For sexgymnastics,  essential.

old: orgasm	new: ecstatic
Male sort of satisfaction had led to delimiting the time-span of intercourse.	As long as possible ecstatic excitement.

old: hypocritical culture

new: healthy life-style sub-culture

The official culture permits only the hidden sexual behaviour.

The healthy, safe sex has no need to be hidden. Anyhow, for the meanwhile, it must be performed in the private of the persons involved (of their own will; the door open for free exit of anybody). The participants should be still aware that they are in private only since an accidental common onlooker (under the spell of the "old" factors) would have consider their behaviour as "kinky", though - in fact - it is healty & safe!

Now, we can see that there are so many factors which prevent us from the new - safe and pleasurable - ways of sex-behaviour...

Yet, "I have a dream" that we overocme them and - instead of alcohol and drogues - people will practise sexgymnastics with heter-handjob in specialized sex-gyms!

To write me your opinion (or your suggestions how to introduce all of them to life), see my contact below the title of this text, please!