"What are you doing?"
Abby jumped, half chocking on the bite of the apple she was munching while scribbling calculus on her notebook.
She coughed for a few seconds, but quickly got over her surprise. She would never get used to the way Nikola constantly crept on her. Especially not at breakfast time.
"Oh my God, Tesla! Will you never get tired of that?" she protested.
He smirked.
"Never." He confirmed, peering down at her formula.
Abby cleared her throat.
"Anyway. I'm checking my target heart rate zone for my cardio workout. I know you do exercise. Have you never done it?"
"I very much doubt the formula would work on me." He stated with a side smile.
Abby raised an eyebrow.
"Let's check." She said resolutely.
He shrugged.
"Do you even know what's your heart rate at rest?" She asked.
"Of course. 45."
Abby's eyes rounded.
"What?"
"I know, right? Divisible by nine. Perfect, isn't it?" He boasted with a smile.
"Are you kidding me? That's freaking low..."
"Vampire, remember?"
"Alright..." She sighed, writing down the number on a corner of her page. "So, you're obviously a man" she added.
"Clever you." He complemented.
"So we take 220, which is the maximal heart rate for men, minus your age..." That's when she realized how stupid it was to even try the formula on him. "Oh..."
"one hundred and sixty four." He grinned. "Please, do go on."
Rolling her eyes, she did.
"56... Minus your heart rate at rest..."
"11" He helped.
"If you want a light intensity training, your heart rate while running should be between 50% and 70% of this number. Let's take 70%."
"7.7" He computed.
"To which you add your heart rate at rest, so 52.7." She finished, grimacing.
He smirked, patting his stomach.
"Now you know why I'm in such a good shape. I'm constantly training." He concluded.
"I'll be the judge of that." Helen's voice rang as she entered the kitchen, already dressed for the day.
Abby's cheeks colored slightly at that. As cute as they were together, she really didn't need the images that simple sentence created in her mind.
"Abby's having fun with the Karvonen formula. Did you know that if you want a light intensity training, your heart rate should be of -24.5 beats per minute?" Nikola asked, turning his head to where Helen was putting the water to boil for her tea behind him.
So he was also counting her heartbeats... How cheesy, Abby thought.
Helen shook her head.
"Really, Nikola? You couldn't have used the age our bodies are stuck at for this?" She retorted.
The vampire winked at Abby when it dawned on her that he had fooled her, again.
"Where's the fun in that?"